The present invention discloses a spacecraft precision measurement method based on a complex irregular shape precise measurement lens. According to the method, through setting a complex precise measuring mirror, the precise measuring optical path in closed cabin interior equipment is led out, and the precise measurement of the high precision equipment in the closed cabin in a whole machine closed cabin state is realized. According to the method, the precision measurement state of the high precision equipment and a flight state converge, the precision error of a traditional closed spacecraft brought by measuring cabin interior equipment in a cabin opening or cabin segment pull state is eliminated, and the effectiveness of precision measurement data is ensured.