Based on the characteristics of scanning beam interference lithography (SBIL), the dynamic exposure model is established for the standing wave effect of the exposure in the photoresist layer. Based on the fast marching method, the development model is established and the evolution rule of grating mask grooves is obtained. In order to reduce the influence of the standing wave effect, a design method for the optimal thickness of anti-reflective coatings (ARCs) is proposed. The simulation results show that the established exposure and development models can effectively predict the groove profile of the grating masks, and optimize the thickness of ARCs simultaneously.