The heavy rainfall and landslide brought by typhoon always cause severe damage in Taiwan. Therefore, the quantitative precipitation forecasting is one of the important topics of disaster mitigation. In 2005, Kidder et al. Proposed Tropical Rainfall Potential (TRaP) which applied passive microwave radiometer to retrieve tropical cyclone precipitation and further predict heavy rainfall caused by tropical cyclone. However, their method did not consider the effects of tropical cyclone rainband rotation and intensity change. Thus, Liu et al. (2008) improved TRaP by considering typhoon rainband rotation. Furthermore, the effect of intensity change was considered in this research. For intensity change prediction, the method of DeMaria (2006) was improved to predict 6-h accumulated rainfall prediction and extend to 24-h accumulated rainfall prediction. After the evaluation with small island observations, it shows that the improvement is significant when considering typhoon rainband rotation and intensity change.