Abstract: ObjectiveIn this study,the germination characteristics and salt tolerance of melon seeds of different varieties under NO3-stress were analyzed to provide reference for screening,improving and utilizing salt tolerant melon varieties.MethodSix melon varieties IVF117,ZY20,IVF198,RX8,FT7 and CL were used as the experiment materials. Effects of NO3- stress at various concentrations on seed germination ,germination characteristics ,osmotic adjustment and root activity of different melon varieties were investigated. Then salt tolerance of these varieties was evaluated by membership function method.ResultLow concentration NO3-stress(67.0 mmol/L)had little influence on germination rate,germi-nation index,main radicle length,hypocotyl length,radical fresh weight,water content,relative electrolyte leakage rate, root activity and salt stress index. However,the inhibiting effect to the indexes were obviously enhanced under high concen-tration NO3-stress(201.0 mmol/L). There were no significant difference(P>0.05)in hypocotyls coarseness and radical dry weight under NO3-stress of different concentrations. Median lethal concentrations(LC50)of IVF117 and ZY20 seeds were 229.36 and 182.57 mmol/L respectively,higher than the others;but LC50 of CL was the lowest(124.34 mmol/L). Compre-hensive evaluation on salt tolerance showed that NO3- tolerance of IVF117 and ZY20 were strong,and that of IVF198, RX8 and FT7 were moderate,but CL was sensitive to NO3-stress.ConclusionIVF117 and ZY20 are salt tolerant melon varieties,which can be planted in NO3-saline area and be used as sources of excellent salt tolerant genes. IVF198,RX8 and FT7 are moderately salt tolerant,and CL is sensitive to salt stress,which needs salt tolerance improvement in cultivation.