Abstract: In this paper, the influences of the monthly mean temperature for Mar-Aug. on the yield of rice in Kunming have been analysed and an index of the low temperature on the cold damage of rice is presented here. It is shown that the strong/weak on the intensity of West-Pacific subtropical high. at 500mb level in the period of Mar.-Aug. is well related to the high/low temperature in the same time in Kunming region and this intensity holds well from Winter through Summer. According to the intensity during Jan.-Feb. we can forecast the intensity for Mar-Aug. and go on with the low temperature forecasting in Kumming area.