Alignment mark search system used for photo-etching equipment and its alignment mark search method

The invention provides an alignment mark search system applied to a lithography device and a search method thereof. The system comprises an optical imaging system, a signal conditioning system and a master control system, wherein, the optical imaging system obtains the image of a datum plate and outputs a first light intensity signal, the signal conditioning system receives the first light intensity signal, adopts a digital potentiometer controller to realize bidirectional voltage regulation and outputs light intensity data, the master control system adjusts the position of the datum plate according to the light intensity data. The alignment mark search system of the invention contributes to accurately obtaining corresponding position information concerning reference marks of machines, carrying out demarcation and correction on machine constants relative to machine mark positions rapidly, shortening correction time of the machine constants after complete installation of the machines and improving efficiency of the complete machines after restoring to normal operation.