【Objective】 To clarify the pathogenicity differences of Rhizoctonia spp. strains isolated from different crop hosts. 【Method】 Twenty R. solani strains were isolated from rice, maize and wheat plants respectively. Their cross-pathogenicities of R. cerealis to rice, maize and wheat were determined by artificial inoculation. 【Result and conclusion】 Each isolate of R. solani and R. cerealis was able to infect these three crops, but the virulences on different crops were quite different. It showed stronger virulence on the original host, while weaker virulence on other hosts. These findings provide an important theoretical basis for the prevention of cross-infection of different plant pathogens in the crop rotation and intercropping processes.