The invention belongs to the technical field of optics, and particularly relates to a spatial phase shift dynamic interferometer based on a liquid crystal spatial light modulator and application of the spatial phase shift dynamic interferometer. The spatial phase shift dynamic interferometer based on the liquid crystal spatial light modulator comprises a He-Ne laser, a first pinhole filtering, a first collimation and beam expanding system, a lambda / 2 wave plate, a polarizing beamsplitting prism, a first lambda / 4 wave plate, a second collimation and beam expanding system, a second pinhole filtering, a polarizing film, the liquid crystal spatial light modulator, a second lambda / 4 wave plate, a standard spherical mirror, a measured mirror, a polarization analyzer, an imaging system, a third pinhole filtering and an optical detector, dynamic testing of an aspheric surface member and a free-form surface member is realized through coded modulation of SLM, the SLM is used for replacing a tinypolarization phase shift array to realize spatial phase modulation, the adjustment is simple, the tiny polarization phase shift array is not required, and the difficulty is greatly reduced. Accordingto the spatial phase shift dynamic interferometer based on the liquid crystal spatial light modulator and application of the spatial phase shift dynamic interferometer, the function of real-time dynamic display is achieved, low energy consumption, easy control and high speed are achieved, the spatial resolution ratio is easier to improve, and high-precision measurement is realized.