Exposure result of scanning beam interference lithography (SBIL) system is closely related to the movement property of the stage. The stage adopts coarse-fine dual stage mechanism to fabricate large-area plane grating with nanometer accuracy. The fine stage is the key point of the movement accuracy of the stage. According to the principle of SBIL, the relationship between interference fringe period measurement accuracy and exposure contrast is deduced. For the period measurement method of interference fringe by moving beam-splitter, the positioning accuracy index of the fine positioning stage is analyzed by considering period measurement accuracy requirements. A controller design method is proposed to realize the positioning accuracies of the degrees of freedom in x, y, θz directions. And the experiment is conducted in the fine positioning stage system. The results show that the positioning accuracy of x, y, θz can achieved ±1.51 nm, ±5.46 nm and ±0.02 μrad, respectively, which can satisfy the SBIL exposure requirements and the interference fringe period measurement accuracy requirements.