Numerical simulation is made on typhoon Bilis and Kaemi(2006),the simulated vapor,dynamic and energy fields are analyzed,and two forecast models for preciptation of landfalling typhoons are summed up.The analysis results show that Bilis was affected by the southwest monsoon and got a lot of vapor and energy supplies,while Kaemi did not have such supplies,so precipitation in the south of Kaemi is smaller than that of Bilis.However,Kaemi caused flood calamity in the middle and lower reaches of Yellow River area when its circulation interacted with the cold air from the north.