Abstract: The distribution characteristics of frost in Guizhou was analyzed, which would provide scientific basis for rational utilization of climate resources and supervise agriculture.The first frost day, the last frost day and the frost free period in Guizhou were analyzed based on the daily minimum temperature of 0 cm of 84 meteorological stations in Guizhou Province from 1961 to 2018 by using linear trend, M-K mutation test and spatial analysis. The results showed that in recent 58 years, the average first frost day and the last frost day in Guizhou was December 2 and February 23, the average frost free period was 291 d, with the rates at 2.34 d·(10a)^-1, 2.95 d·(10a)^-1 and 5.76 d·(10a)^-1, showed significant trends of delay, advance and extension (P<0.01), respectively. In the spatial distribution, the first frost day showed the characteristics of earlier in the west, later in the east, earlier in the north and later in the south, 69% of the sites showed a trend of significant delay. The last frost day showed the characteristics of earlier in the south, later in the northwest and northeast. The frost free period was generally prolonged, and 82% of the stations passed the significance level test. Altitude was the key factor affecting the first frost, the last frost and the frost free period in Guizhou, the frost free period decreased with the increase of latitude and altitude. The first frost event occured later, the last frost event occured eailer, and the frost-free period becomed longer, which would provide sufficient heat resources and more favorable agricultural production in Guizhou.

Key words: the first frost day, the last frost day, frost-free preiod, Guizhou, climatic characteristics