1. Patients repeatedly have doubts about the correctness of their own words and actions, which leads to compulsive checking behavior. For example, the patient repeatedly checks whether the doors and windows are closed after going out, or whether the letter is written to the wrong address, etc. 2. Patients repeatedly think about some things in daily life or natural phenomena, tracing them back to their roots, knowing that they are meaningless, but they cannot control them, and their thinking is often entangled in some problems that lack practical meaning and they cannot get rid of them, which can only be seen in teenagers, such as thinking “why do you call a table a table instead of a chair? “Why is one plus one equal to two but not three? 3. When the patient hears or sees a certain idea or a certain phrase in his mind, he involuntarily associates it with another idea or phrase. It refers to the patient’s worry or nausea about something, knowing that it is not right, but unable to extricate themselves. For example, they worry that they will hurt people, say the wrong thing or act irrationally or worry that they are contaminated with bacteria. 4. The patient repeatedly experiences a strong inner urge to do some kind of action or behavior against his or her will. Although the patient knows that this is a ridiculous idea and that he or she will not do so, he or she cannot get rid of this inner urge. For example, if the patient walks along the river with a child in his arms, the intention of throwing the child into the river appears. 5, the patient’s mind often appears opposed to the reality of the concept, this is often bad against the usual moral code of content, for this reason the patient feels nervous, fearful and uneasy but can not exclude, and sometimes even have the impulse to blurt out, such as cursing foul language.