An E-P flux is computed based on the monthly mean data of 200hPa and 500hPa in the Northern Hemisphere winter(January)from 1951 to 2000.According to the cross-section diagram of the E-P flux ,the effect of wave motion on basic flow and the propagation of the planetary-wave due to wave-stream interaction under orographic influence are investigated.The divergence or convergence of the E-P flux in the Northern Hemisphere winter(January)is corresponding with the trough and ridge generated by the orographic effect,and their intensities are also consistent with each other.In addition,the relation between E-P flux and abnormal weather is obtained in line with the link,which is gained from the monthly mean(1951-2000)data of geopotential height,wind and rainfall in summer(July)in the Northern Hemisphere,between E-P flux and subtropical high.