Abstract: The sub- critical R134a( 1,1,1,2- tetrafluoroethane) was employed to extract sea- buckthorn seed oil in the study.Based on the single factor screening involved the granularity of seed,the extracting time and the temperature,the response surface method( RSM) was exerted with three influential factors ranged in each individual optimal level,with the seed oil exacting rate as indicator.The optimized parameters of extraction were as follows: the granularity of seeds was 32 meshes,the extracting time for 60 min,the extracting temperature at 55 ℃.Under the conditions above mentioned,the extracting rate of sea- buckthorn seed oil reached to 80.7%.The iodine value,peroxide value,acid value and VEcontent as( 178.83 ± 0.54) g /100 g,( 0.151 ± 0.001) g/100 g,( 3.412 ± 0.112) mg KOH/g,( 198 ± 1.73) mg/100 g respectively.The quality of the extracted seed oil met the criteria of the industry standard( SL493- 2010). The iodine value and vitamin E content exceeded the lower limit with 27.74% and 65% higher. The peroxide value and acid value were 39.6% and 77.25% lower than the high limit. It was suggested that the extracting of sea- buckthorn seed oil with sub- critical R134 a performs as higher yield,lower processing cost and good quality.