The study on the effects of daytime sub-high temperature (30 and 35 degrees C) in spring and autumn on the growth, development, yield and quality of greenhouse tomato in northeast China showed that compared with the plant growing under feasible temperature 25 degrees C, three days' daytime sub-high temperature increased the relative growth significantly, and made the plant spindling. Seven days or more sub-high temperature made the plant grow fast, with thinner leaves and presenility. Under sub-high temperature, the harvest time was earlier, the fruit weight and the 2nd and 3rd inflorescence lessened, the quality of fruit decreased, and the yield decreased significantly. Sub-high temperature had a strong influence on the normal growth and development of greenhouse tomato. The longer the plant suffered sub-high temperature from flower bud differentiation to fruit maturing, the worse the fruit quality, and the lower the yield would be.