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The variation trend of the safe growth period for rice in recent 40 years over the southeastern Guizhou Province is analyzed on the basis of the daily mean air temperature data of 16 meteorological stations from 1961 to 2000. The results indicate that the rice safe growth period decreased by 7 days in recent 40 years over the southeastern Guizhou, by 10.6 days, 6.4 days, and 4.8 days for altitudes below 400 m, 400 to 600 m, over 800 m, respectively. On the contrary, at the altitudes between 600 m and 800 m, the growth period increased by 1.4 days. In the 1980s, the growth period decreased obviously with the minimum in 1980. In conclusion, the rice safe growth period took on an slight increasing trend at altitudes between 600 m and 800 m, and an obvious decreasing trend at altitu des below 600 m, as well as over 800 m.