Classical Genetic Algorithms(CGAs)accomplish the global search by selection, crossover and mutation. It has many shortages. Here we proposed a restricted genetic algorithm based on ascending of tangent plane (RGAATP). Our algorithm is simple and effective, which approaches the global solution step by step by ascending of the tangent planes. It is proved that the algorithm is global convergent, and it can solve the optimization of multimodal function [6] easily and effectively. The experimental results show that its performance is more stable and efficient than aSGA.