Under the condition of intelligent artificial climate chamber, the effects of extreme high temperature on the seed setting rate of hybrid rice and it's fertilizer-water regulation were studied with five hybrid rice combinations as tested materials. The results showed that the average daily temperature above 33℃ at booting stage and heading stage had significant effect on the seed setting rate of rice. When the temperature was above 38℃, the seed setting rate dropped sharply. At the heading stage, when the temperature reached 38℃, the seed setting rate of the tested varieties was below 10%. The effect of high temperature on booting stage was significantly smaller than that at heading stage. Under the conditions of average daily temperature of 33℃ at booting stage, the yield loss of the tested varieties was less than 10%, while 33℃ at heading stage, the yield loss was about 65%. Under 38℃ conditions, the yield loss of high temperature at booting stage and heading stage was about 80% and 90% respectively. There were significantly or extremely significantly positive correlation between seed setting rate and plant chlorophyll content and soil relative water capacity under the condition of high temperature. Increasing the nutrient level of the plant and keeping the shallow water layer in the paddy field could significantly alleviate the yield loss caused by high temperature.