Incubation rhythm and nest defense behavior of the Chinese Sparrowhawk (Accipiter soloensis) were studied with the aid of infrared camera during two successive breeding seasons of 2016 and 2017 in Dongzhai National Natural Reserve of Henan Province. Totally 52 nests were found and 661 306 pictures were taken during the two seasons. The breeding success rate was 51.35% (n = 74 eggs) with nest failures recorded (Fig. 1), and the King Rat Snake (Elaphe carinata) being the main predator. With the observer served as an intruder by climbing the nest tree, we recorded the nest defense behavior of 15 couples for 10 min sorted into four different nest defense levels, i.e., level Ⅰ (never approach to the nest tree except alarming), level Ⅱ (threaten people by diving but do not touch the tree leaves), level Ⅲ (threaten people by diving and touch the tree leaves), and level Ⅳ (attack people) (Fig. 2). The results of analyses showed that: 1) the males′ nest defense level exhibited extremely significantly positive correlations to both their incubation frequency (r = 0.751, n = 15, P < 0.01) and incubation time (r = 0.803, n = 15, P < 0.01), and a significantly positive correlation to the total incubation time (r = 0.527, n = 15, P < 0.05). Meanwhile, the females′ nest defense level also showed an extremely significantly positive correlation to the male birds′ incubation frequency (r = 0.717, n = 15, P < 0.01) and a significantly positive correlation to incubation time (r = 0.619, n = 15, P < 0.05, Table 1); 2) the males′ nest defense level showed an extremely significantly positive correlation to that of the females (r = 0.743, n = 15, P < 0.01) (Spearman rank correlation); 3) the average absent time was significantly negatively correlated to both incubation frequency (r =﹣0. 680, df = 11, P < 0.05) and incubation time (r =﹣0. 640, df = 11, P < 0.05) of the males as well as incubation time (r = ﹣0.558, df = 11, P < 0.05) of the females, but showed an extremely significantly negative correlation to the total incubation time (r =﹣0.772, df = 11, P < 0.01) (Partial correlation) (Fig. 3). In conclusion, the more investment in incubation taken by the Chinese Sparrowhawks, the stronger nest defense behavior they demonstrated. In addition, male and female defense behavior were similar, possibly due to mate choice or learning from each other.