The stool becomes thinner after hemorrhoid operation. I don't know what to do.

This situation is normal. If the stool becomes thinner, it may be related to your surgical method. For example, this will happen after PPH, so your specific treatment method is not clear, so it is not good to give a specific answer here.

If possible, I suggest you consult a local doctor. If I don't give you better advice, I suggest you go to the local 3A hospital for an anal examination after the anus is fully recovered, and check whether it is due to anal dysfunction caused by surgery.