The polyunsaturated fatty acids (PUFAs) were extracted from hempseed oil by combined technology of ethyl esterification and molecular distillation. The molecular distillation conditions of the product were studied. The results of ethyl esterification showed that when alcohol amount 80 mL, NaOH 1％, temperature 70 ℃, reaction time 30 min, the yield of hempseed oil fatty acid ethyl ester was the highest and the form of PUFAs was best preserved. The results of molecular distillation showed that when vacuum degree 2.0 Pa, distillation temperature 90 ℃, it had a good enrichment effect. The content of PUFA ethyl esters raised to 82.09%, recovery rate was 79.28%. The results of multi-stage molecular distillation showed that after four stages molecular distillation, the PUFA ethyl esters were purified up to 87.91%, recovery rate was reduced to 53. 91%.