Abstract: Under 50 mmol·L^-1 NaCl stress condition, we studied the relaxation effects of sodium nitroprusside(SNP, an exogenous nitric oxide donor) at the contents of 0.05, 0.1, 0.5, 1.0 and 2.0 mmol·L^-1 on germination and physiological metabolism in Catharanthus roseus seedlings. The results showed that NaCl stress inhibited the germination of C.roseus and SNP could alleviate its stress effect. At the 0.1 mmol·L^-1 of SNP the seed germination, germination and vitality index, and contents of proline in leaves were increased significantly, while malondialdehyde(MDA) content in leaves were decreased dramatically. Nitrate reductase(NR) activities in 0.1-0.5 mmol·L^-1 SNP groups reached to higher levels compared to that of control group. However, more than 0.5 mmol·L^-1 SNP enhanced the stress effect of NaCl. Therefore, the 0.1 mmol·L^-1 was the most appropriate content for SNP to alleviate NaCl stress. In conclusion, appropriate contents of exogenous NO could alleviate NaCl stress on C.roseus seeds and seedlings effectively.