In blasting vibration monitoring at Nanshan thirty-fifth step of Dexing copper mine in Jiangxi,the data recorded by three vibration measuring devices with the same parameter is greatly different with each other.This paper briefly analysis the propagation law and stress loss of stress wave when it goes from one medium to another medium.It was concluded that the water on blasting step can reduces the vibration velocity of blasting earthquake wave and the extent of vibration velocity dropping is associated with wave resistance of two different medium,the weakening effect of water on vertical vibration velocity is great,but is not obvious on horizontal vibration velocity.