Abstract: Under the background of global climate warming, based on the meteorological data, early rice production data and early rice agro-meteorological observation data from 2005 to 2016, the authors calculated high temperature (≥32℃) hours and thermal accumulated temperature at grain filling stage, in order to explore the regularity and effects of high temperature damage on 1000-grain weight of early rice in Hainan. The results indicated that: the high temperature hours and thermal accumulated temperature at grain filling stage of early rice both increased annually in Hainan, and could be fitted by logarithmic function, with the correlation coefficients of 0.69 and 0.68 respectively. 1000-grain weight decreased with the increase of high temperature hours and thermal accumulated temperature, and the rate of descent slowed down gradually.