Abstract: Effects of grafting on the growth, nitrogen metabolism, osmoregulatory substances and soluble protein expression was conducted with pumpkin (Cucurbita maximaCucurbita moschata) as the rootstock and a cultivar cucumber Jinyou No. 3 as the scion under iso-osmotic Ca(NO3)2 or NaCl stress. Results showed that the rootstock-grafted seedlings significantly enhanced the growth, NR activity, NO3--N, soluble protein, soluble sugar, proline content and decreased NH4+-N content under iso-osmotic Ca(NO3)2 and NaCl stress. SDS-PAGE profiles show that there were twelve differentially-expressed proteins in leaves of rootstock-grafted seedlings in present of salt treatment. Of these twelve proteins, ten proteins were up-regulated including the proteins of relative molecular weight (103) for 188.4, 156.1, 120.4, 54.0, 37.3, 32.1, 30.6, 18.9, 17.8 and 17.1 while one proteins of 81.0103 were down-regulated and turned a novel protein of 63.4 103. And thus, we considered these twelve proteins were related to enhancement of salt-tolerance rootstock-grafting in cucumber seedlings. Results also showed the expressing of four proteins of relative molecular weight (103) such as 86.1，23.4, 18.9 and 17.8 were stronger in both self-grafted and rootstock-grafted seedlings under NaCl stress than that under Ca(NO3)2 stress, whereas the expressing of proteins relative molecular weight (103) such as 188.4, 156.1, 54.0 and 17.1 were lower under NaCl stress than that under Ca(NO3)2 stress. And three proteins of 39.1103, 35.4103 and 21.2103 even disappeared in self-grafted seedlings under NaCl stress for 9 days. It was possible that these eleven proteins have relations with rootstock-grafted seedlings improving the Ca(NO3)2 stress tolerance of cucumber seedlings．In conclusion, the damages caused by NaCl stress were more serious than that by Ca(NO3)2 stress, and rootstock-grafting could effectively alleviated the injury via regulating nitrogen metabolism and osmoregulatory substances of cucumber seedlings under salt stress. It seems this catabatic fuction in rootstock-grafted plants was more expressing under Ca(NO3)2 stress.