A side window is usually adopted by the kinetic kill vehicle (KKV) operating in higher atmosphere as a basic layout. The engagement result is gravely influenced by the side window orientation which involves many factors. On the basis of some ideal hypothesis, the regularity of the line-of-sight variation rate is investigated, and the effect of the attack angle induced by the orientation is analyzed theoretically. Consequently, the optimal direction of the side window orientation is educed as the aerodynamic force taken into account only. Subsequently, the law to determine the orientation directions at all fighting altitudes are put forward, when the aerodynamic force, the divert and attitude control system are concerned. The numerical simulation result shows that this method can meet the side window detection command and the KKV only needs one orienting action to finish the interception in most circumstances.