Analyses shows that the mean monthly temperature can't describe the chilling climatic characteristics in winter of Hainan because of the big interdiurnal temperature variation. Based on the growing conditions of crops, the climatic probability of chilling damage appeared on Hainan island (example Haikou) was calculated and it was put forward that there are relative winters in Hainan. Further, the cold index was introduced instead of the mean temperature to desciribe the chilling characteristics in Hainan's winter. The PCA expressed that there is obviously difference of chilling in winter between North and South of Hainan island divided by the Wuzhi mountain which lifts and detains the cold air to go southward. It also indicates that the appearing probability of the heave and middle degree chilling damage is 100% in the cold winter and the appearing probability of the heave degree chilling damage is 100% in the extreme cold winter from 1960s. Analyses on the 500 hPa circulation of the extreme cold winter indicates that it would be the extreme cold winter in Hainan island when the polar vortex lied on the shore of Arctic Ocean of the eastern Siberian.