Abstract: Method of using radish seedling as plant host to propagate peach aphid for mass rearing Aphidius gifuensis was studied in the laboratory. Results showed that the most favorable condition for the propagation of peach aphid was 20-25℃ and RH 70%. A. gifuensis prefered to oviposit on peach aphid of younger instars and the parasitization rate was also higher. 25℃ was the most favorable temperature for parasitizing. The host: parasite ratio could influence the parasitization rate. Best result was obtained when 100-200 aphids∶1 pair of parasite was used and 80% of the aphid could be parasitized. Continual rearing of A. gifuensis on peach aphid for 10 generations would decrease the parasitization rate of the aphid, but no distinct ill effect on the younger instar aphid was noted. Satisfactory results were obtained in a rearing room using radish seedling as plant host to propagate peach aphid for mass rearing A. gifuensis. Considerable amount of Aphidius wasp was obtained in a short period and used for the control of peach aphid.