Abstract: The tobacco aphid or peach aphid is the major insect pest of tobacco in Yunnan.The present paper deals with life cycle,habits and reproductive capacity of the braconid parasite of aphid (Aphidius gifuensis Ashmead).This parasite completes its life cycle in the laboratory at 25-27℃ between 9-13 days,in which the egg stage 1-2 days,the larval stage 4-5 days,the prepupal stage 1-2 days,and pupal stage 3-4 days.The longevity of adult fed with honey is 9 days.The average number of parasitized aphid was found to be about 127.6 by one female.The number of matural eggs in the ovary is with and average of 169.9,max.433.Liberation of the indigenous braconid parasite of aphid to control the tobacco aphid was proved to be highly effective through the laboratory and field experiments during 1976-1977 in Yuxi.In oder to determine the result of control,about 120,000 of braconid parasite of aphid have been released in 20 Mu of tobacco field in 1978.The result of field test showed that the percentage of parasitization was obviously increased from 0-95%,whereas that the population density of aphid decreased to lower levels after the liberation from 34.3 to 0.1 (average) per plant,and that for the control,the percentage of parasitization was gradully increased from 0.1 to 38.8.Whereas that the population density of the aphid obviously increased,from 33.2-51.2 average per plant,(maximum 440.5).The result was much better than the spraying of the poison,Roger,at a dilution of 1:1000.The mass rear of the Aphidius gifuensis Schmead has been reproted.