Mianyang Three Diagnostics is a mock exam of college entrance examination, which aims to let candidates feel the atmosphere of college entrance examination in advance and improve their ability to cope with college entrance examination. Mianyang Three Diagnostics is organized by the local education examination institutions, and its direct relationship with the college entrance examination lies in that it can help candidates better understand the examination forms and difficulties of the college entrance examination, better master the examination skills and strategies, and thus improve the results of the college entrance examination. In addition, some colleges and universities will also refer to the results of three clinics in Mianyang as one of the admission criteria. Therefore, it is very important for candidates who take part in the college entrance examination to take part in Mianyang Three Diagnostics.