Abstract: Describes the mechanism of rain field interference in radio proximity fuzes, including the capacitance fuzes. The interference comes mainly from raindrop deformation when a raindrop collides with the fuze, the medium ' s influence on the interference being neglected. Through analysis and experiments, 3 main factors of rain field interference on a proximity fuze have shown up, namely the diameter D of raindrop, the colliding position and the relative velosity between the raindrop and the fuze.