An optical path splitting 2 D shearing interferometric opto electronic measuring system is introduced. The tests in two orthogonal directions can be implemented at the same time and the automation of data processing is achieved with the system and the simple method of digital integration can be well adopted in the wavefront reconstruction by taking a series of steps of removing noise and subtracting the mirror surface datum before and after the deformation. The measuring standard error is below 0.257 μm within ±10 μm range of the deformation and the sensitivity is 0.05 μm. The deformation dynamic tests of high power laser resonator mirror was successfully demonstrated in real time.