The invention discloses an urban rail transit assembly board type high precision rail base cast-in-place construction method. The method comprises the following construction steps of 1 CPIII rail foundation measurement and control network establishment, 2 track center line setting out, 3 substrate treatment, 4 equipment walking rail installation, 5 base reinforcement manufacturing and installing, 6 base template and expansion joint installation and limiting boss position reservation and 7 assembly board type high precision orbit base concrete construction. Accordingly, a CPIII rail foundation measurement and control network measurement and control technology, an intelligent sensing technology and a precise hydraulic control technology are integrated, intelligent precise pounding up equipment is adopted, assembly board type rail roadbed base concrete pouring is intelligentized and mechanized; the problems that artificially poured large-area concrete elevation control is difficult, the surface evenness is poor, and the quality is unstable are solved, and the high precision assembly board type rail base is manufactured; by means of the method, the mechanical operating rate is increased, the labor intensity of workers is reduced and lightened, and the work efficiency is improved.