Abstract: Based on the daily maximum temperature data of 40 meteorological stations in the Huai River Basin from 1960 to 2020, the spatial and temporal variation characteristics of heat wave frequencies, duration days and effective accumulated temperatures in the Huaihe River Basin are analyzed by using the methods of linear regression and Morlet wavelet analysis. The results show that 3 444 heat waves occurred in the Huaihe River Basin in the 61 years from 1960 to 2020, including 64.26% mild heat waves, 22.68% moderate heat waves and 13.06% severe heat waves. High temperature heat waves occurred 56.46 times a year in the Huaihe River Basin, with an annual average duration of 6.79 days and an annual average effective accumulated temperature of 11.04 ℃. The total heat waves for different grades in the Huaihe River Basin showed marked periodic features during those 61 years. Heat waves were most and strongest in the 1960s, showed a decreasing (weakening) trend before the mid-1980s, and then turned to an increasing (strengthening) trend since mid-1980s. During those 61 years, the main variation cycle of heat waves was 20 years, and the minor variation cycles were respectively 27 years and 9 years in the Huaihe River Basin. The spatial distributions of heat wave frequencies, duration days and intensities were similar, which decreased (weakened) from west to east; the high value areas were concentrated in the southwest parts of the Huaihe River Basin; and the low value areas were concentrated in the northeast parts. From the perspective of the change trend, the frequencies, duration days and intensities of heat waves showed a decreasing (weakening) trend in the west of the basin, and an increasing (strengthening) trend in its east.