In order to study energy output rule on attenuation of small diameter charge detonation wave passing by air-gap,the detonation shock wave pressures of different charge diameters and confinements,which are attenuated in air-gap,are measured by using the manganin piezoresistance method.Thus the experiential attenuation rule of X booster explosive is obtained with confinement of 45 # steel and polymethyl methacrylate(PMMA),the experiential relational expressions in charge diameter and air-gap thickness are gained.The results indicate that exponential rule is obtained in accordance with attenuation of small diameter charge detonation wave passing by air-gap,and the bigger charge diameter,the smaller modulus decay.By changing air-gap thickness,the detonation pressure is also changed.The detonation performance can be controlled by adjusting charge dimension,confinement and air-gap thickness.