The invention provides a method for evaluating the surface roughness of a prefabricated floor of a concrete laminated board, which belongs to the technical field of assembly building performance evaluation. Compared with a traditional method, the method has the advantages of high accuracy and uniformity. The method comprises the specific steps that (1) calculation of the roughness equivalent valuemu i of a measurement zone: test sand of volume V is spread on the rough surface of the prefabricated floor, and when the sand is spread, the test sand is completely filled into the gap of the roughsurface, and the paving area S is measured and calculated, mu i=V/S; (2) calculation of the roughness depth mu of the rough surface of a member: mu =k*mu c, wherein k represents the estimated coefficient and mu c represents the roughness equivalent value of the member, and according to K=shi/vi, s represents the upper surface area of a rough surface model, hi represents the height of the rough surface model, and vi represents the volume of the rough surface model, and (3) if the roughness depth of the rough surface of the member mu is greater than or equal to 4.0 mm, the member is judged to be qualified.