The trifluoromethylcarbene (:CHCF3) was found to be conveniently generated from (2,2,2-trifluoroethyl)diphenyl-sulfonium triflate (Ph2S(+)CH2CF3 (-)OTf), which was successfully applied in Fe-catalyzed cyclopropanation of olefins, giving the corresponding trifluoromethylated cyclopropanes in high yields.