Based on NCEP reanalysis data,the paper used the mesoscale numerical model MM5 to carry out the forecast work of rain and temperature in the Yellow river.It analyzed the forecast effectiveness of the typical precipitaion process in the Weihe river in 2011 and the temperature in the Inner Mongolisa section and downstream of the Yellow River in 2011.The result indicates that the forecast of precipitation distrubution and strength,as well as the magnitude and the location of heavy rainfall center in the Weihe river is in good accordance with the real situation.MM5 products can correctly reflect the spatial distribution characteristics of flood season precipitation in the Weihe river;for the temperature forecast, with the increase of forecast period, the error increases, but the mean error range is in the scope of permissible error. The forecast effectiveness is the best Especially for Baotou staion which is the key site in the ice regime forecast of the Inner Mongolisa section.