Abstract: Scleroderma guani and Scleroderma sichuanensis were bred by utilizing 2.0 cm to 3.0 cm long larvae of Monochamus alternatus.The inoculation was conducted with three parasitoid-host ratios(2:1,3:1 and 4:1),and the indexes such as infecting rate,shriveled rate of host,parasitical rate,successful parasitical rate,quantity of oviposition and the number of bethylid filial generation were determined.The results showed that 3:1 parasitoid-host ratio was the best choice for breeding these two species of ethylids regarding to each index mentioned above.The breeding efficiency ratios of the two bethylid species were 1.00:1.98:1.36 and 1.00:2.79:1.49 respectively.So the parasitoid-host ratio of 3:1 was thought to be the optimal ratio among the three treatments.