Speckle shearing interferometry is an important tool for dynamic surface deformation measurement, which in combination with spatial phase shift technique can make the method more useful in practice. More attention is paid to the spatial carrier frequency method based on Fresnel bi-prism which can measure the slope of deformation instantaneously. The application of Fresnel bi-prism can obtain a spatial carrier speckle interferogram. The shear distance and carrier frequency generated by the bi-prism are analyzed. A slit is used to control the speckle and produce the carrier in one speckle size. The calibration of carrier is implemented by Fourier analysis method, and the sinusoidal fitting method is used for actual measurement of slope. The experiments show that this method can be conveniently used in spatial phase shift speckle interferometry and is suitable for dynamic measurement.