Abstract: The installation accuracy of the fluid floating coupling and its optimal control are studied in this paper. Through the analysis of the error sources, the maximum error among the active and passive floating couplings is obtained. And then an optimization control method of the installation accuracy is proposed to directly control the fluid floating's installation accuracy under the docking mechanism coordinates. According to this method, the floating ability target of a floating coupling is determined. The effectiveness of the method is verified by the ground inserting/separating test.