The accuracy and time of initial alignment of shipborne weapon strapdown inertial navigation system (SINS) determine the accuracy and speed of weapon system attack. Because the navigation environment of ship is complex and changeable， the strapdown inertial navigation system (SINS) of shipborne weapon uses the high-precision navigation information provided by the ship's main inertial navigation system (MINS) for traction alignment， which can improve the accuracy and speed of alignment and ensure the smooth completion of combat tasks. In this paper， the performance of shipborne weapon strapdown inertial navigation system using the position and velocity information provided by the main inertial navigation system is analyzed by semi physical simulation， and the alignment performance is evaluated by using the attitude tracking accuracy and time of the main inertial navigation system after the traction alignment. Through the analysis， it is concluded that under static conditions， after the traction transfer alignment is stable， the heading reference transfer error caused by traction transfer is less than 1.8′(0.03°)， and the attitude reference transfer error is less than 10.8″(0.003°). Under the dynamiccondition， when the traction transfer is stable， the heading reference transfer error caused by traction transfer is less than 2.4′(0.04°)， and the attitude reference transfer error is less than 10.8″(0.003°). This paper provides a certain reference for the establishment of the traction alignment model of each subsequent combat platform.