Simulating the climate characteristics of high temperature and humidity in summer and micro freeze thaw in winter in Hangzhou, based on factors of cycle number and temperature, dry wet and freeze thaw(DW FT) cycling test in indoor was designed. Short term aging of neat asphalt and SBS modified asphalt was carried out by thin film oven test. Fourier transform infrared spectroscopy(FTIR) and gel permeation chromatography(GPC) were used to analyze the change of the characteristic functional groups and relative molecular mass distribution of asphalts under the action of the DW FT cycles in order to explore the water aging characteristics of asphalt. The results indicate that, with the increasing number of DW FT cycle, the oxygen aging characteristic peaks of the carbonyl index change little under the condition of mild oxidation(60℃), the sulfoxide index increases obviously, while the butadiene index of SBS asphalts decreases obviously. The number average and weight average relative molecular mass, polydispersity and the large molecule size(LMS) content increase gradually. So the sulfoxide index and LMS can be used to characterize the water aging degree of the asphalts. Both FTIR and GPC results show that the effect of the DW FT cycles in water environment can accelerate the water aging of asphalts, and the SBS modified asphalt has greater water aging resistance than the neat asphalt.