Abstract: Effects of 35℃sub-high temperature in daytime from the 1st flower efflorescence and 10 days after efflorescence on the phenophase, yield and quality of tomato in the greenhouse were studied. The results showed as follows, long time sub-high temperature in daytime advanced the phenophase of plant and made the plants senescence earlier. The fruit-set ratio, weight of per fruit and the yield and quality of fruits under sub-high temperature all decreased. Results showed that the earlier the plants suffered sub-high temperature from the 1st flower efflorescence, the worst did the growth and development and the quality and yield of fruits.