Abstract: For the basement of tall，Superhigh and complex multi-layer structure，with basements the following issues are the most important ones for designers in analysis and design of these kinds of buildings，such as how to consider the effect of partial fixing in basement，and how to rationally simplify the computation model of the structures． Aiming at verify the reasonability of basement roof as partial fixing in high structure standard，this article analysed the lateral structure chosen at random in the basement of the lateral stiffness and stiffness ratio of superstructure floor basement．