[Objective] Tomato is one of the fruit and vegetable crops cultivated with the highest economic benefits in open fields and greenhouses. It is of great necessity to explore salt tolerance of germinating tomato seeds and its mechanism, especially changes in polyamine metabolism in the seeds.[Method] In this study, Impacts of NaCl stress on seed germination percentage (SGP) and development of radical and hypocotyl, seed water content (SWC), seed vigor index (SVI), Malondialdehyde (MDA) content, protective enzyme activity, solute accumulation and contents of various forms of polyamine of/in the seeds of tomato, "Hezuo 903" in variety were studied.[Result] When the soil was treated with 25 or 50 mmol·L^-1 NaCl for seven days, germination of tomato seeds was slightly delayed, but SGP was not affected, however, SVI of the tomato decreased significantly. With rising salt concentration in the treatment, both the SGP and SVI decreased significantly. With SGP and SVI cited as dependent variables, and NaCl concentration in the treatment as independent variable, salt tolerance threshold for seed germination and seedling establishment was 106.1 mmol·L^-1 NaCl (0.62%) and 43.38 mmol·L^-1NaCl (0.25%), respectively. With rising NaCl concentration, MDA content, soluble protein (SP) content and the activities of enzymes like SOD, POD and CAT in germinating seeds were increased significantly, also, the contents of fPut, fSpd, fSpm, (fSpd+fSpm)/fPut, bPut, bSpd, and bSpm in the germinating tomato seeds all increased significantly, but (bSpd+bSpm)/bPut did not change much. Compared with the seeds in CK, the seeds treated with 50 mmol L^-1 NaCl did not change much in conjugated Put (cPut), but increased significantly in the contents of cSpd, and cSpm and the ratio of (cSpd+cSpm)/cPut. With increasing NaCl concentration, the seeds declined gradually in cPut, cSpd, cSpm and (cSpd+cSpm)/cPut. It was also found that salt stress significantly reduced the content of total polyamines (TPAs) and free total polyamines (fPAs) in germinating tomato seeds, but increased the content of free total polyamines with rising NaCl concentration.[Conclusion] Salinity delays and even inhibits germination of tomato seeds, and has a much stronger inhibitory effect on establishment of the seedlings after germination. Tomato seeds per se have certain salt tolerance during their germination phase mainly due to the drastic increase in (fSpd+fSpm)/fPut, cSpd, cSpm, and significant accumulation of all the forms of bound polyamines, SS and SP in the seeds under salt stress, thus raising the seeds' antioxdation and osmotic adjustment capacities. However, when salt reaches as high as 150 mmol·L^-1NaCl, the effects of salt stress raising cSpd and cSpm weaken, while the effects raising bound polyamine of all forms, fSpd and fSpm, and regulating SS and SP accumulation are still intensify.