In the context of global warming, the likelihood of concurrent heat waves is expected to increase in most parts of China, which will have social and environmental impacts. However, heat wave characteristics are likely to vary regionally. Based on maximum daily temperature and relative humidity data from 134 meteorological stations for the 1960-2016 period, the spatiotemporal variation in heat waves was investigated for the Qinling-Huaihe region. We also analyzed the relationship between El Nino-Southern Oscillation (ENSO) and heat waves. We found that the heat waves in the past 57 years in the study region can be characterized as nonsmooth and non-linear. Three distinct phases of decadal change were identified. During the first phase (1960-1972), with 112°E as the dividing line, heat waves were highly variable with alternating highs and lows in the western part of the region, but occurred at high frequency in the eastern part. During the second phase (1973-1993), heat waves showed low-amplitude fluctuations across the entire region, and rapidly increased in the mid-1980s. The third phase (1994-2016) saw high-amplitude fluctuations in heat waves in the western part of the region, but heat waves decreased in the eastern part. Our results show that over the entire region, the extremes in heat have been more sensitive to daily maximum temperature than regional relative humidity changes. Thus, the cooling of daily maximum temperature along the Huai River led to a decreasing heat wave spatial extent. There was also a notable difference in the relationship between ENSO and heat waves in the Qinling-Huaihe region: a strong positive correlation in the north and a weak negative correlation in the south were observed. Particularly, heat waves on the Guanzhong Plain have been closely related to Nino 4, whereas the relationship has been weak along the lower reach of the Yangtze River. The Nino 1 + 2 and Nino 3 indices showed significant negative correlations with heat waves across the lower reach of the Yangtze River. In the lower reach of the Yellow River and Qinling-Daba Mountains, the variations in heat waves have been weakly correlated with equatorial Pacific sea surface temperature anomalies. In addition, there has been more close relationship between temperature anomalies of equatorial Western Pacific and decadal variation of heat waves on the Guanzhong Plain in recent decades, which has contributed to enhanced warming on the Guanzhong Plain and along the lower reach of the Yangtze River.