Day sunny and night rainfall in summer is a typical kind of compound extreme events at daily scale. The study of response relationship between the intensity of summer day sunny and night rainfall (DSNR) and climate warming, is of great importance for the control of soil erosion in China’s north-south transition zone. Based on daily precipitation data in summer (June to August) of 72 meteorological stations, assisted by B-G segmentation, empirical orthogonal function (EOF) method and Lasso regression model, we analyzed the spatiotemporal variation and influencing factors of the intensity of DSNR at summertime in the north and south of Qinling mountains during the period 1970-2020. The results showed that: (1) From 1970 to 2020, the intensity of DSNR in summer exhibited a significantly increasing trend, which was more obvious in Hanjiang River Valley (0.30 mm/(d·10a)). (2) The leading mode of the intensity of summer DSNR was characterized by “consistence in the whole region, with a higher degree of anomalies in the valleys than in the mountains”. It indicated that valley-plain areas were sensitive to variations in the intensity of DSNR at summertime. Temporally, between 2003 and 2020, the spatial pattern of “lower in the north but higher in the south” in the intensity of summer DSNR is changing, and consequently Guanzhong Plain and Hanjiang River Valley have become high value areas of increasing summer DSNR intensity in the north and south of Qinling mountains. (3) In terms of influencing factors, the correlation between evolution in the intensity of DSNR at summertime and meteorological factors in the Hanjiang River Valley and southern slopes of Qinling Mountains was higher than that in Guanzhong Plain. In addition, cumulative duration of sunshine was the leading climatic factor driving the changes of summer DSNR intensity in the northern slopes of Qinling Mountains, while the variations of summer DSNR intensity in the Hanjiang River Valley was jointly influenced by cumulative duration of sunshine and average wind speed. To be specific, the intensity of DSNR at summertime in the southern slopes of Qinling Mountains and Hanjiang River Valley showed a positive change relationship with cumulative duration of sunshine and average wind speed, respectively.