The main features of China's ancient censorship of Cai show its limitations.

1, Single-line verticality: One of the most obvious features of the ancient supervisory system in China is that supervisory organizations at all levels from the central government (emperors and monarchs) to local governments form a relatively independent system with single-line verticality (single-line connection and single-line leadership). This supervision system centered on imperial power determines the relative independence and separation between supervision and administration (including central, local and even grassroots), the relative separation between central and local supervision institutions and government agencies, and the separation between supervision officials and government bureaucrats. So as to ensure the independent operation of supervision power, the integration of supervision institutions and the effective exercise of supervision officials.

2. Lofty status: In China's traditional political system, to effectively implement political power, it is necessary to have a certain political status or enjoy higher political power to supervise the executors of political power. In order to ensure the effectiveness of the work of supervisory organs, it is another remarkable feature of China's ancient supervisory system to give supervisory officials senior supervisory status. This feature makes the ancient supervision in a very favorable position, makes the operation of supervision independent of administration, and effectively exerts the supervision of administration.

3. Selection of officials: First, the law of supervision activities. In ancient China, supervisors were generally called "constitutional officials" or "judges" and usually followed the principle of "judges". When exercising their supervisory power, supervisory organs and supervisors shall take the law as the criterion and supervise according to law. Secondly, China's ancient supervisory system has another feature that can be used for reference, that is, it attaches importance to the selection and appointment of supervisory officials and their quality.

limit

As the supervision system in ancient China was the eyes and ears of the emperor, a tool of imperial power and a system that restricted bureaucrats, such a supervision system would inevitably lead to a direct historical limitation: Who would supervise the emperor? Although the supervision system in ancient China was vertically independent, its power came from the emperor, and its independence was relative to the bureaucratic system, so it could never be independent of the emperor. For example, the popular impeachment system in China's ancient supervisory system only had the supreme ruler-the emperor, which was in obvious contrast with the contemporary country ruled by law. A direct consequence of this historical limitation is that emperors living above the supervision system can only rely on personal rationality and ability to restrain themselves. However, man's rationality and ability are limited, and so is the emperor. This can not only ensure that the emperor himself does not make mistakes, but also ensure that the emperor consistently maintains the normal operation of the supervision system. In addition, from the perspective of comparative supervision system, such historical limitations led to the design of the supervision system in ancient China to strengthen imperial power, not to represent the will of citizens, not to protect and extend civil rights, nor to limit and supervise monarchical power.

Different from modern civil servants, China ancient bureaucrats had a strict division of labor, and they were a group with political, administrative, legislative and judicial privileges. In order to effectively supervise such a privileged group, it is necessary to strengthen the ancient imperial power supervision system and make the supervision power independent of bureaucratic power. However, the characteristics of the unipolar centralized political system produce a supreme imperial power (monarchical power), so it is impossible to form a multi-power supervision structure based on the separation of the highest power, which is both vertical, horizontal and even two-way. In this way, the checks and balances of power, the rule of law and even the supremacy of law will not come out, and the mutual restraint of power and democratic supervision will not come into being. Therefore, China's traditional national political system structure is not only the main reason for the strengthening and development of the ancient supervision system, but also another trap that leads to the historical limitations of the ancient supervision system. The characteristics of this traditional national political system lead to the supremacy of imperial power and the unrestricted supreme power of the state. So that the government that assisted the emperor in governing the country also had corresponding unlimited power. This power structure characterized by vertical restriction and supervision is often weak, and sometimes even ineffective, because of the lack of horizontal power checks and balances at each level. China's ancient officialdom's "bullying the upper and deceiving the lower", "protecting officials" and local protectionism all reflect this power structure.