Alfalfa,considered as the king of forage,is the most important legume in the world. However,the root rot of alfalfa has become a primary restraint of its wide utilization at present. The main pathogen of the root rot of alfalfa is from Fusarium,of which,F. oxysporum, F. solani and F. avenaceum are dominants in intruding roots. As a useful application of disease resistance breeding,with advantages of aim-orientation and high efficiency, biological technology has drawn increasing attention.