Abstract: The method presented in this paper is an approximate optimization method for nonlinear objective function. Based on point to point linearization, it is optimized by the gradient method. Inverse matrix calculation is simplified by the concept of orthogonal test and orthogonal table in this process. This method possesses the advantages of calculation in small amounts, rapid search and insensitive to initial value. With this method, satisfactory result has been obtained in the design of the stationary system for an inertial guidance platform.