Abstract: Pyrus betulifolia dormant seeds were soaked and treated for 24 hours with the different concentrations of Sodium nitroprusside (SNP), 2-phenyl-4, 4, 5, 5-tetramethylimidazo-line-1-oxyl-3-oxide (PTIO),Sodium tungstate(Na₂WO₄) and ZhiN^G-n-L-arginine methyl ester (L-NAME),and the percentage germination was calculated in the training process,aiming to find effects of Nitric oxide (NO) and the synthesis pathway of nitric oxide on seed dormancy of P. betulifolia. The results were as follows:NO could break the seed dormancy for germination of Pyrus betulifolia,10 mmol·L^-1 of SNP treatment was better in promoting germination,the germination rate of seeds pretreated with 10 mM SNP reached 56.7%,significantly higher than the control(20.0%); In breaking the dormancy of Pyrus betulifolia seeds,NO came from nitric oxide synthase(NOS) but not Nitrate reductase(NR) pathway,the germination rate of seeds pretreated with L-NAME was 15.6%, significantly higher than the control, but Na₂WO₄ Pretreatment didn't have any effect.