The susceptibility of two strains of alfalfa leaf-cutting bee to Beauveria bassiana was studied in laboratory.The bivoltine adult died faster than the univoltine adult under 28℃ and RH 60% after treatment,the mortality was 67% and 38% at 72 hours respectively.There was significant difference on susceptibility between two strains of the bee to B.bassiana.The bivoltine adult was more susceptible to Beauveria bassian（P＜0.05）.