This paper put forward a kind of predigest laser combine bind and extend bind flat roof structure, which is founded as fission flat roof, and can be built in an little room 1280mm×990mm×815mm. This flat roof space location can be adjusted. This kind of seat can ensure the system complete laser combine and close as high precision. In this paper we designed the laser combine and close whole structure and install design. At last we did some finite statics analysis to some important parts. This design can ensure every laser fire directional adjust mete lower ±30′, and the flat roof quality is 770kg. The transition benchmark flat roof system most meet and emergency is 0.005mm at the premise of bear the weight of turn flat laden. It can be seen that this structure can satisfy the request of many lasers small space laser extend bind and adjust. This kind can be extended to other light combine bind and extend bind structure design.