Abstract: Increasing of extreme hot weather has been witnessed in China in the past several decades. Rice is generally considered to be seriously threatened by hot weather, especial frequent occurrences of extreme hot weather. Though the rice heat disaster is widely studied, researches on temporal characteristics of early rice heat are lacking. It is of great merit to explore the rice heat-lead characteristics of hot weather processes, and highlight the particular period severely hit by rice heat to provide support for rice heat monitoring, prevention, and mitigation. Therefore, maximum temperature, disaster and phenological data on rice in Jiangxi are integrated to construct the historical early rice heat samples from 1981 to 2016. Nine sets of rice heat samples are built in the context of combinations of different hot weather duration (3-5 d, 6-8 d and more than 8 d) and heat levels (light, moderate and severe). Afterwards, Kolmogorov-Smirnov (K-S) and information diffusion method are adopted to analyze starting and ending dates of rice heat and their orders comparing with heading, and to explore rice heat occurring possibility and characteristics of rice heat in different level. Results show that the occurrence time of heat disaster is approximately 6 d before heading stage to 20 d after heading stage. It is with great possibility of 36.73% for heat disaster to start in 1-5 d after heading and 18.37% in -4 d-0 before heading and 6-10 d after heading. Effects of high temperature on early rice gradually decrease as the mature stage starts, with 5.61% rice heat occurring in 15 d after rice heading. The probability of moderate and light heat damage is more than 80% when 3-5 d of hot weather occurs and increases to 98.77% when more than 5 d of hot weather occurs during heading-flowering stage. It is identified that light rice heat mainly occurs in 3-17 d after heading, moderate rice heat occurs in 2-12 d after heading and severe rice heat occurs 2 d before heading and 9 d after heading. Converting to early rice phenological data, the above is concluded that major occurrence periods for light rice heat is from heading to mid-grouting stage, moderate rice heat in stage of heading to early-mid grouting and severe rice heat from booting to early grouting stage.