Abstract: In recent years, high temperature disaster occurred frequently in China, which had a serious impact on maize and became one of the main meteorological disasters endangering maize production. Based on daily maximum temperature observation data of 110 meteorological stations in the region from 1970 to 2019 and observational data of the summer maize booting period from 19 agro-meteorological observational stations in Henan province, the occurrence days, frequency and disaster risk of high temperature disaster were analyzed by using statistical and spatial analysis methods. Four key meteorological factors were selected to build integrated climatic indexes. The indices included the occurrence probability of temperature higher than 32℃ and 35℃, and the accumulation of temperature higher than 32℃ and 35℃. The results showed that: (1) the days and occurrence probability of temperature higher than 32℃ and 35℃ decreased from 1970s to 1980s, and increased since 1990s. The days of high temperature in 2010s during the summer maize flowering period was increased by 1.4d (≥32℃) and 1.5d (≥35℃), and the occurrence probability increased by 20.6 percent point (≥32℃) and 20.5 percent point (≥35℃). The days of high temperature during the summer maize flowering period was from 1.8 to 4.5d (≥32℃) and from 0.4 to 1.9d (≥35℃), and occurrence probability of high temperature was from 24.3% to 64.3% (≥32℃) and from 2.5% to 31.1% (≥35℃). The spatial distribution has significant difference, and the frequency in the southeastern was higher than other areas. (2) The accumulation of temperature higher than 32℃and 35℃ showed an increasing trend after decreased in the early stage. Compared with the 1980s, the accumulation of temperature in 2010s increased by 52.8℃·d (≥32℃) and 52.5(≥35℃). The accumulation of temperature higher than 32℃ was from 56.7℃·d to 156.4℃·d during the summer maize flowering period and that of higher than 35℃ was from 15.9 to 79.1℃·d, and accumulation of temperature in south was higher than that in the north, and it in the east was higher than that in the west. (3) Integrated risk indexes showed that high risk was mainly located in southeastern areas, which adjacent to the south part of Nanyang, Luohe, the east part of Xuchang, and Zhoukou, accounting for approximately 28.5% of the main summer maize planting area. The risk was moderate in the central region, accounting for approximately 56.2% of the main summer maize planting area. While the risk of heat stress was relatively low in Sanmenxia, Anyang and in the western part of Luoyang and Jiyuan, accounting for approximately 15.3% of the main summer maize planting area.

Key words: Summer maize, High temperature disaster, Risk zoning, Henan province