The invention discloses a laying precision detecting method of a CRTSIII plate-type ballastless-track track board, and belongs to the technical field of track construction. The laying precision detecting method comprises the following steps that scanning data of n detecting stations of the ballastless track are obtained through a three-dimensional laser scanning device; track bearing table position scanning data of each detecting station, scanning data of targets mounted on the two pairs of CPIII on the front and rear of each detecting station are processed by using a grayscale recognition algorithm, the track bearing table center position coordinates and the target center position coordinates are obtained; the absolute coordinate of a CPIII net and the structure height of a standard trackare guided into, and an actual line shape of the rack is fitted; the designed line shape of the track and the curve segment track super high value are guided into, deviation value data of the actualline shape position and the designed line shape position of the track at any section position of the track board are calculated; and a material list of fastener parts corresponding to the track bearing table ID numbers in a one-to-one mode is generated according to the deviation value data. The laying precision detecting method improves the work efficiency of CPISIII plate retest, reduces the replacement rate of the standard fastener parts, and saves the cost.