For long-focus TMA space camera that connect to satellite platform horizontally, the connecting interface temperature difference between satellite platform and space camera is generated due to the alternation of ground test and in-orbit condition, leading to the line-of-sight drift of the space camera which effects imaging quality. In order to solve this problem, the optimized connection method that applying flexible connector, rigid connector and releasable connector cooperatively was proposed. The space camera was flexibly and statically determinate installed on satellite platform in orbit, and the connection stiffness was enhanced by two additional releasable connectors in launching stage so that the fundamental frequency was ensured. The optimized connection method was verified by finite element method, the secondary mirror angular deviation caused by satellite platform temperature decreasing 15 ℃ was 9.62″(the span of installation locations was 1.2 m), which satisfied the optical tolerance. In launching stage, the fundamental frequency of space camera in X, Y, Z directions was 120 Hz, 120 Hz, and 110 Hz, there was no significant decreasing compared with rigid connection. The alternative experiment of platform temperature ascending 15 ℃ was performed via experiment fixture, the test result was consistent with the simulation, the maximum relative error of secondary mirror angular deviation between measurement and simulation was 9%. The results show that the problem of line-of-sight drift caused by satellite platform and space camera temperature difference is solved by optimized connection method, and in-orbit environment adaptability of camera is improved.