A heavy rain at the rear of typhoon Rananim is analyzed, based on the observations mesoscale automatic weather stations data in a mesoscale network, regular meteorological, 1°×1° NCEP reanalysis dataset and CINRAD Doppler radar data. The results reveal that after typhoon landing, the intensively ascending motion of middle-upper level and intensive and continuous moisture transport in lower levels caused the heavy rain in northern Wenzhou and southern Taizhou. The analysis radar echo shows that the spiral cloud bands of typhoon is the direct reason which caused the heavy rain at the rear part of typhoon.