Osmotic conditioning of sweet pepper (Capsicum annuum L.) ‘Shapphire’ seeds by polyethylene glycol (PEG ) 6000 showed that primed seeds germinated and emerged more rapidly than untreated ones in both laboratory and field tests. The time to 50% of final germination (GT50) and time to 50% of final germination and emergence (GT50 and ET50 ) of primed seeds reduced by 5.24 to 1.23 days (GT50) and 7.74 to 2.78 days (ET50), respectively. Priming did not significantly shorten the spreading time of 10 to 90% of final germination and emergence (GT90 - GT10 and ET90 - ET10) for ‘Shapphire’ seeds. Interaction effects among priming concentrations, temperatures and treatment duration were significant on seed vigor. Second order response surface regression model could demonstrate the variation trend of seed viability after priming for cultivar ‘Shapphire’. The optimum priming conditions were -0.7 ~ -1.0 Mpa PEG, 17~23℃ and 4~7 days for ‘Shapphire’ seeds.