To obtain the rules of jet penetrating spaced target with water interlayer,theoretical and experimental research were performed selecting the penetrating process of 50 mm caliber shaped charge penetrating spaced target with water interlayer (2 mm×4 mm steel plates +100 mm water interlayer). The theoretical model of jet penetrating spaced target with water interlayer was established by quasi-steady penetration theory and mathematical induction,the relationship of jet tip velocity and penetration distance was got. To validate the theoretical model,jet tip velocities of multiple stages were obtained by X-ray pulsed and timing device. The influence of spaced target with water interlayer to the remaining jet tip velocity was analyzed through theoretical model. The results show that the theoretical model is correct,after penetrating spaced target with water interlayer,the average error of remaining jet tip velocity between theoretical and experimental values is 4.6%.The attenuation efficiency of jet tip velocity by spaced target with water interlayer is higher when the target thickness is less than 20 mm and water separation distance is less than 150 mm.