The process of extracting pyrethrin from pyrethrum flower includes the following technological steps: a. crushing pyrethrum flower, 40-mesh sieving, setting inside polyethylene film bag and adding n-hexane for soaking the material; b. sealing the bag, setting the bag inside high pressure container and applying pressure of 50-600 MPa at normal temperature for pressure leaching of 1-30 min; c. relieving pressure, filtering the extracted liquid to obtain the filtrate; and d. concentrating the filtrate to obtain the pyrethrin extractum. The said technological process has the advantages of high extraction rate, short technological process, low power consumption and low apparatus investment.