Abstract: Many key components of power system installed in the newly designed naval ship are firstly developed. Quality of installation is of great importance to the project. Reduction gear box installation requires a more effective means as to fulfill the stringent precision requirement. This paper gives a description of accuracy controlling technology applied to the actual measurement in ship. In this method, plane-equation is adopted for the adjustment of reduction gear box. It shows that this method is simple and cost-effective. The results provide a reference for the installation activities.