The tilapia（

Oreochromis spp

.）is very important for fishery in China. China is the first in the amount of product and export of tilapia in the world every year. The period of tilapia’s maturation is very short. So the reproduction is very fast and waste a lot of energy. The style of mono-male cultivation can resolve the problems. In this paper

the researches have been concentrated on the male rates under different water temperature condition in larva Nile Tilapia（

Oreochromis niloticus

L.）. The possibility of making mono-male by temperature controlling has been discussed from two aspects: the effective temperature and the disposal duration time. The larvae were treated from 7DPH. Two factors were considered: the water temperature（20 ℃

28 ℃

36 ℃）and the disposal duration time（7-14DPH

7-21DPH

7-28DPH）. They were taken into account by orthogonal experimental design. The main results are as follows: at the aspect of getting monomale by temperature control

when the temperature is 36 ℃

the male rates in the three disposal duration（7-14DPH; 7-21DPH; 7-28DPH）are significant higher than the other treatment schemes（P＜0.05），the male rates are 93.85%

96.00% and 96.92% respectively. In order to evaluate the effects of masculinization

the growth rates and the survival rates have been studied too. When the treatment schemes (temperature + disposal duration time) are 36 ℃+7-14DPH

the AGR and survival rate are no significant difference with the Control Group（P

>

0.05）. In general

the best treatment schemes are 36 ℃+7-14DPH

the average male rate is 93.85% and the highest male ratio is 96.96%. The growth rate and the survival rate in that treatment schemes are normal too.