A proton microprobe with high resolution and high sensitivity was applied to analyze atmospheric aerosol in the people's park in Shanghai urban for single particle source apportionment. The results showed that the sum of the average contribution rates from the sources of soil dust, building construction dust, vehicle exhaust and metallurgical industry, which are the main pollution sources of atmospheric aerosol in Shanghai urban and surpasses 80%. Besides, about 13% of the particles could not be identified. On the basis of cluster analysis of these particles, they are preliminary known belonging to two different individual sub-pollution sources and a new unidentified pollution source.