The attenuation of infrasound wave propagation in the atmosphere has been researched in this paper. According to the different profiles of temperature, density and pressure,the inhomogeneous medium model of atmosphere has been established.By using the WKB(Wentzel,Kramers,Bril louim) approximation method,the Helmholtz equation has been solved under the inhomogeneous medium.The infrasound wave field distribution has been analyzed through this method，and the calculation of infrasound wave attenuation in the troposphere atmosphere has been carried out.The main factors influencing the infrasonic attenuation in different geographical area have been compared.