Typhoons are the most serious weather system that strike Taiwan annually. There are about four or five typhoons that affect Taiwan every year and bring destructive winds and extreme rainfalls. They can seriously cause damages of agriculture, industry and human casualties. Historical records show that on the average, there are about 26-27 typhoons form in this area each year and among them three to four may invade Taiwan. This study propose novel procedures facilitate GPS network PPP derived ZWD for investigating the characteristics of extreme rainfall triggered by typhoons, the temporal and spatial relationships between GPS network PPP derived ZWD and rainfall is essential. Since typhoons can move as fast as 20 km/hr, a time frequency analysis tool coupled with a sensor network that can detect the event taking place within an hour is desired for a small island such as Taiwan. The extreme torrential rains often bring numerous rainfalls so that causes great casualties and economical loss. The cross correlation analysis is applied with GPS PPP estimated ZWD series and accumulated precipitation series collected at those sites during Typhoon Morakot Typhoon Sinlaku to investigate their spatial and temporal relationships. In addition, the time and frequency analysis including FFT and CWT are applied to investigate the characteristics of extreme rainfalls triggered by those typhoons.