A method for wavefront stitching detection,in which small-aperture Hartmann-Shack wavefront sensor is used to test large-aperture optical system or component,is proposed. The basic principle is to divide large wavefront into certain small ones;then,the slope data in the overlap regions are used in a linear least squares fitting routine to obtain stitching parameters between each sub-frame and the benchmark frame. These parameters are then used to construct the whole gradient map,which is later used to reconstruct the whole wavefront by modal algorithm. The mathematical model of comprehensively optimized stitching mode is established and verified in our experiment. A H-S wavefront sensor with valid aperture 37.5 mm is adopted to test a plane reflector′s 60 mm area and the stitching result is compared with the whole-aperture wavefront that directly acquired by an interferometer. The RMS value of the error wavefront is 0.04 λ and the algorithm accuracy reaches up to λ/40. It proves that the comprehensively optimized stitching mode could be used in large optical surface measurement.