| This paper presents a novel model of lane allocation optimization for signalized isolated intersection,considering different approaches, movements, and lane function use as well as the effect of their interactions. The mathematical model takes into consideration the constraints, including the number of approach lanes, number of exit lanes，flow conservation，lane markings of approach lanes，and equalized degree of saturation. The optimization model aims at the least critical flow factor and the least minimum variance of flow factors for arm. For shared-lanes, constraint equations of equalized degree of saturation are established according to different lane-use patterns. Finally, the optimization model is verified by the actual data of intersections, which lays a theoretical foundation for the development of signal control aided design software.