The electron swarms parameters of trifluorometha-nesulfonyl fluoride (CF3SO2F) with a low value of global warming potential (GWP) of 3678 were measured for a range of reduced electric fields (per gas density N) E/N from 400 to 750 Td at room temperature (20 degrees C). The discharge parameters such as the reduced Townsend first ionization coefficient alpha/N, the reduced attachment coefficient eta/N, and the reduced effective ionization coefficients (alpha-eta)IN are obtained by using the steady-state Townsend method. The comparison of the experimental results with those of SF6, a kind of the most widely used insulation gas, indicates that CF3SO2F has a better insulation performance than SF6 because of a much higher reduced critical electric field of 578.8 Td.