The both sides of macro-and micro-symbionts were studied for host plant Bradyrhizobium strain compatibility of the cultivated peaunt.The results showed that (1) Bred cultivar was better than virginia type in nodulation and NZ fixation when the host plants were inoculated with strain 147-3 in greenhouse under condition of water culture.(2) Five serotype strains were determined by using agglutination in test tube and FA-indirect method.Nodulation competition and recovery were closely related to host cultivar.Rhizobium strain and indigenous rhizobium population.(3) The different host plant Bradyrhizobium strain combinations varied in the widely/sepecifically symbiotic compatibility and incompatibility.A widely compatible cultivalr,Xuzhou 68-4 with highly efficient nodulation and N fixation by strains tested,was identified,and a strong compatible strain 147-3 with broad host range was also indentified in greenhouse and field experiments.(4) The strong compatible cultivar-strain combinations produced significantly(P<0.05) higher pod yields than the incompatible combinations or uninoculated control.of 205 site trials for inoculation compatible combinations in the different parts of China from 1987-1990,the frequence of yield increase was 97%,the average yield increased by 421.5kg/ha,15.1%,compered with uninoculated control.