Based on the gyro free strapdown inertial attitude measurement principle of missile system is analyzed. From the point of view of engineering installation, this paper puts forward a kind of simple installation method of the nine accelerometer which can realize the gyro free strapdown inertial navigation system. The simplicity and rationality of the nine accelerometer configuration scheme are analyzed. The calculation principle of the guiding principle of installation of the nine acceleration are deduced based on the detailed calculation of the algorithm of GFSINS, which proves the feasibility of the nine accelerometer configuration. Finally, the mathematical model of angular acceleration and linear acceleration is established. On the assumption that there is no random white noise and constant error,through the MATLAB simulation, the angular velocity and angular velocity error of the system are given ,and it is proved that the configuration of the nine accelerometer is simple and feasible.