The effect of feeding 17a-methyltestosterone(400 and 800ppm)over a period of 45 days，starting with 3-day-old fry，or. growth and gonadal developme. of allogynogenetic crucian carp was investigated. After the treatment， the tested fish was reared with hormone-free diet for one year. The experimental results are as folhws:Oral administration of 17a-MT at 400 and 800 ppm resulted in a high percentage of sterile fish. The ratio of sterile fish was 3.71 times and 3.40 times as high as control group. In comparison with the control group，the mean body weight in two experimental groups increased by 16%and 11%，respectively. The mean gonadosomatic index decreased by 45.5%and 24.500，and the mean percentage of dress-out increased by 6.5%and 5.0 %，respectively. Any germ cells were not been found in the thread-like gonad of sterile fish. The results suggest that oral administration of 17a methyltestosterone at 400 ppm and 800 ppm to allogynogenetic crucian carp fry would result in androgenic castration and production of sterile fish，especially at the 400 ppm. The level of testosterone in serum and muscle of two experimental groups had no significant difference with control group，indicating the hormone-treated fish do not contain any residual hormones and they are quite safe for humanconsumption.