Abstract: Using the 1°×1° reanalysis grid data of NCEP, two northward typhoons “Bolaven”and “Muifa” which are similar to the path but quite different in precipitation when they reach Jilin Province are compared with traces and other physical factors in this paper. It is found that the subtropical ridge of the Western Pacific decided whether the typhoon moves northward or not. The precipitation caused by typhoon is related to the value of vapors brought about, and the vapor flux divergence value was suitable in the precipitation forecast. The vertical structure of typhoon especially the baroclinic configuration of vorticity benefits for the development of typhoon. Western wind trough and cold air affects the typhoon for the precipitation intensity. The configuration of high and low air jet is a guidance whether the typhoon system continuous maintaining and where the heavy rain occurs, and it is a key issue related to the intensity and duration of precipitation.