Abstract: An experiment on NWP/Satellite retrieval/Data assimilation was described in the paper.Since the method of water vapor retrieval was improved and the accuracy of retrieval relative humidity (RH) has been increased,the retrieval RH wasonly used in assimilation.The result show safter 4-step 6h assimilation the typho on intensity modelled was more consistent with that of the real one than withoutret rieval R H.Although the trend of decreasing of the typhoon intensity for ecasted for 48h ahead is weaker on the low levels,it is better than the modelling withoutret rieval RH.It is evident that the retrieval RH had positive impact on the analysis and forecast of typho on intensity.The forecast both 24 and 48 hahead of total precipitation and the rainst or mintensity in the centre of rain areas were increasing and close to the real ones when the retrieval R H was used.