Based on a spatial light modulator(SLM) and the approximately linear relationship of exposure curves the approximately linear model of optical transmission coefficients of gray-scale masks has been established,and the accurately controlling strategies for precision of gray levels were given.The corresponding experiments were accomplished by using sliver halide holographic recording material,and two-levels,eight-levels and sixteen-levels masks of Fresnel lens were manufactured.The error caused by blurred effect at the edge of gray-scale masks was analyzed,and the basic way to overcome the influence on precision of gray levels owing to nonlinear effect was proposed.The accurately controlling model for precision of gray levels,which has been established in this paper,has an important guiding significance to ensure parallel manufacturing precision of gray-scale masks.