Abstract: During 6 to 7 October 2013, typhoon "Fitow" and typhoon "Danas" affected on the region of East China, causing regional heavy rainfall. By using objective separation and numerical simulation methods, we distinguished the roles of each typhoon at their different stages. Results showed that regional heavy rainfall on 6 October, for which objective separation and numerical simulation agree with each other, was caused primarily by typhoon "Fitow". For regional heavy rainfall in northeastern Zhejiang province and southeastern Jiangsu province on 7 October, objective separation results showed that the two typhoons have played a critical role. However, simulation results indicated that heavy rainfall was directly related to typhoon "Fitow", while the role of typhoon "Danas" was very limited. Frontogenesis function showed that cold air had also played a role in the heavy rainfall.