In order to eliminate the measurement error caused by the support of the subaperture stitching interferometry, the method of maximum likelihood estimation is proposed to calculate the deformation due to the support. The first step is to maintain the brace immobility, rotating the test lens to measure the subaperture surface. Then, the maximum likelihood estimation method is used to calculate the deformation caused by the support. Finally, the interferometer measurement data of the subaperture surfaces subtract the estimated support surface error, and the stitching algorithm is used to splice a full aperture surface shape. The experiment results are compared with the result of the full aperture direct interferometer measurement, which shows that the method can remove the deformation caused by the support and improve the accuracy of the stitching detection.