Characterization of the formation and size distribution of nano-size aerosol formed from Dimethyl Sulfide（DMS）and corresponding photooxidation intermediate of SO2 is vital to understand the role of DMS in global climate change. Photooxidation of DMS was carried out in a 14 L White cell chamber by UV exposure and high purity air dilution. A combination of Wide Range Particle Spectrometer（WPS) and in-situ FTIR spectrometer was used to measure the produced secondary aerosol and gaseous species.