Sand soil from Sanjins town of Fuyu county,Jilin province,was used as the experimental Soil.Through some pot culture experiments and field experiments such as collection of peanut nodule bacteria,strain separation and purification,and returning inoculation of original host varieties,some good strains and their combinations that suit different peanut varieties of Jlin province were selected,and the yield increasing mechanism of peanut -peanut root nodule symbiosis nitrogen fixation was clarified preliminarily.Superior nodule bacteria varieties of 2644,2656 and 2697were selected,and through pot culture experiments,their physiological and chemical characteristics were identified.The results show that2644was quick-growing type of nodule bacteria,demonstrating comparatively strong nitrogen-fixating ferment activity.2656 and 2697 were slow-growing types of nodule bacteria,with a relatively strong nitrogen fixation activity.The above results rectified the conventional opinion that peanut nodule bacteria do not have a quick-growing type or the quick-growing type has a lower nitrogen-fixating ferment activity.At the same time,a better effect could be obtained when two or more than two of the three superior strains were combined together.They were better -selected strains suitable for application in peanut production.This provides theoretical foundation for the introduction of superior nodule bacteria varieties and inoculation combination.