Traditional methods are difficult to fabricate the gray sinusoial grating in structured-light three-dimension projection measuring system, and if replaced by Ronchi grating will affect the measurement accuracy. A novel method for gray sinusoidal grating plate fabrication is presented. Through the analysis of transmittance curve of holographic silver halide plate, the reason that sinusoidal interference pattern of contrast degree for 1 can not be linearly recorded and transformed is pointed out. A new method of linear recording is proposed,which provides a pre-exposure uniformly incoherent light bias point. The experimental results show that the sinusoidal interference fringes record of symmetrical two-beam can be obtained by the spatial filtering method, and the linear and high contrast record of sinusoidal interference fringe can be achieved by exposure controlled accurately in the linear region of the holographic silver halide plate.