Six ROPs related gene mutants were found through screening mutants library of the Lotus retrotransposons 1 insertion (http://users/mb.au.dk/pmgrp).Different homozygote M1 and M2 generation seeds were obtained by the isolation and PCR identification.Results of identification and statistical analysis of M2 generation symbiotic phenotype showed that the root nodules primordium numbers per plants of rop-like1 homozygote were significantly decreased compared with those of wild type.Both the numbers and density of infection threads per plant in rop-like4 homozygote were also significantly decreased.The nodule numbers of rop-like1 homozygote decreased significantly in comparison with those of wild type after 14 days inoculation.It will provide evidence for further studying ROPs function and regulatory mechanism in rhizobium infection and the process and development of nodules organs.