The definition, importance and research issues of High-efficiency simulation for Complex system are proposed firstly in the paper. The application demands for the development of high-efficiency simulation technology for complex system are discussed from two aspects, which are the demand from Complex system modeling and simulation for high-end users and that of Providing "cloud simulation services" for massive users. 8 important technologies in current high-efficiency simulation for complex system from three aspects, which are high-efficiency simulation modeling technology, high-efficiency simulation system and infrastructure technology and high-efficiency simulation application technology, are introduced in detail, including (1) High-efficiency simulation language for complex system, (2) High-efficiency simulation algorithm for complex system; (3) Hardware Optimization of high-efficiency simulation; (4) High-efficiency simulation software support technology; (5) High-efficiency cloud simulation technology; (6) VV&A technology on high-efficiency simulation system for complex system, (7)Massive data management technology, (8) Simulation experiment results analysis and evaluation technology for complex system. Conclusion and recommendation are given at the end of the paper.