Alfalfa leaf-cutting bee,Megachile rotundata F.,is the most important pollinator for alfalfa seed production and soybean crossing.After a brief introduction of Alfalfa leaf-cutting bee been given,the history and development of its study at home and abroad was summarized in the paper,including researches in the field of voltinism,diapause,relationship between voltinism and diapause,and the natural enemies in its reproduction.