To meet the requirement for missile by modern warfare, the missile's strike density as well as the precision should be improved for missile's lethality improvement. Due to geomagnetic field, the projectile's posture in the air was affected, the aerial projectile's posture was measured with magnetic resistance sensor, the mathematical model of the projectile's posture in the air was established by the quaternion method, and Matlab was used for the simulation of the projectile's posture in the air. Through simulation, the ideal posture of the projectile in the air was calculated, thus the ballistic was corrected, and it would improve the missile's strike density as well as the precision greatly so as to meet the technical requirements by modern war.