genes including RbohA(Lj5g3v1497840),RbohB(Lj6g3v1549190) and RbohC (Lj5g3v1497820) were found to be primarily expressed in nodules based on the transcriptions of Rboh genes in symbiosis in Lotus japonicus. Their function involved in symbiosis were further studied in Lotus japonicus.The subcellular location of proteins,the expression pattern of Rboh genes,the proteins function and the promoter activity of Rboh genes in Lotus japonicas were studied with methods of molecular biology,cell biology and genetics. The results showed that LjRbohA,LjRbohB and LjRbohC proteins were localized at the plasma membrane.The transcript of LjRbohA,LjRbohB and LjRbohC accumulated abundantly in roots and nodules. The activity of LjRbohA and LjRbohB promoters were detected at vascular tissue,nodule,and the lateral root primordia.The numbers of nodules were reduced in LjRbohB,LjRbohALjRbohC  and LjRbohALjRbohBLjRbohC knockout transgenic roots compared with control transgenic roots. It is indicated that these three Rbohs might have an overlapping function in regulating nitrogen fixation symbiosis in L. japonicus.