Aiming at the status about vertical target precision of projectile and the hitting accuracy of the first round artificially measured, the magnetic resistance sensor was referred to be used to perceive the change of strength and orientation from the magnetic field during projectile passing. In order to realize non-contact measurement about the fall/impact point of the projectile, the law of correspondence relations between the change of magnetic resistance and poison of the projectile was researched and found, and the result of preliminary study of the fundamental structure of the positioning system, which is based on the embedded analysis of the operational principle of this test, will be shown to lay the foundation to improve the ways and means of the base test and develop testing equipment.