Nutrient solution culture was used to M82 tomato salt sensitive variety as experimental materials. With twodimensional electrophoresis (2DE), we studied the salt conditions and processing tomato seedlings under salt stress protein expression profile，and identified the differences of protein separation and mass spectrometry trough tandem timeofflight mass spectrometry (MALDITOF/TOFMS) technology. The results showed that: (1) there were 20 protein spots presenting to express differentially after the total proteins were separated by 2DE. The 17 proteins of all presenting spots were upregulated，and 3 proteins were downregulated. (2) Among the 20 protein spots，the annotations of the 19 differential expressed proteins were known by mass spectrometry and protein database retrieval，Identified differential proteins took part in fructosebisphosphate aldolase，SadenosylLmethionine synthetase，glyceraldehyde 3phosphate dehydrogenase，etc，and three unknown functions of protein. These identified the differences of proteins involved in energy metabolism， photosynthesis，protein synthesis，redox balance and other related process，suggested that these proteins may be involved in the salt stress response of tomato，which lay a foundation for further research the mechanism to understand plant stress resistance.