The invention discloses a splicing detector geometry correction body model and a correction method thereof. The method comprises the following steps of S1, installing a geometry correction body model on a splicing detector top surface so that metal round dots on a geometry correction body model substrate are uniformly distributed a photon counting chip; S2, taking the photon counting chip as an unit, dividing a photon counting detector top surface into a plurality of module groups, and according to positions of the metal round dots, calculating center coordinates of all the metal round dots in each module group; S3, calculating a pixel of each module group image, according to the pixel of each module group image, determining whether a seam exists between the adjacent module groups, if the seam exists, entering into a stepS4; otherwise, the seam does not exist, the image does not need to be corrected; and S4, calculating a pixel number of the seam existing between the adjacent module groups and restoring the pixel at the seam to the image. By using the method, actual image detected by the splicing detector can be effectively corrected and image accuracy is ensured.