Radar measurement error is a main factor affecting the hand over precision during terminal guidance of the air defense missile weapon system, and the method to synthesize and evaluate the error is the key point in the weapon system research. Pointing at the common methods of error synthesis, the statistical results of each error synthesis method are analyzed, and the applicability of each error synthesis methods is studied. The radar flight calibration data are used for verification, which can be taken as the basis of the weapon system precision chain design.