The global mediumrange NWF system, T213L31, in National Meteorological Center, CMA, is found to exist the problem of systematic low about 2m temperature. In order to solve this problem, the sources of error of the model system are analyzed. Though a series of analysis, such as comparison of the topography height between model and observatory, and the analysis of two kinds of initial value from EC and CMA operational model land surface model, and so on, it shows that the error of 2m temperature is due to the difference of topography height between model and observatory, and incorrect initial soil moisture which is substituted by specifical value.