Large trough solar reflector surface has large size and high measurement accuracy requirements, which needs high precision measurement method to reconstruct its 3D shape. In order to improve the detection accuracy and efficiency of the large trough solar reflector surface, a large trough solar reflector shape detection method is proposed and implemented based on large scale photogrammetry technology. In the view of the large trough solar reflector surface, at first the convex envelope detection method is used to select non-collinear image points, then the five points relative orientation method is used to solve the relative external parameters of the cameras and the bundle adjustment method is implemented for the optimization iteration of 3D coordinates of measuring points. Finally, the information of the parabolic surface fitted by the measuring points and the design parameters of the reflector are compared and analyzed, then the shape detection of large trough solar reflector surface is completed. Using the proposed method, a measurement experiment is conducted on the trough solar reflector with the size of 12.0 m×5.7 m×1.4 m, the results show that the root mean square error of the measuring points on the reflector is less than 0.033 mm, the average z-axis error and the standard deviation of the fitted parabolic surface are 1.050 mm and 1.466 mm, respectively. These data can meet the surface shape detection accuracy requirements of large trough solar reflector, and the feasibility of the photogrammetry method is verified.