Natural products with good antioxidative properties have been paid increased attention globally. However, due to its chemical complexity, it is difficult to find out its antioxidative compounds. Herein, the chemical profiling and antioxidant capacity of CiNingJi (CNJ) were analyzed, as an example. By using UHPLC-Q-TOF/MS, a total of 82 compounds were tentatively deduced. Furthermore, its free radical scavenging capacity was assessed by different in vitro spectrophotometric-based assays. The result showed that one ingredient, Rosa roxburghii, plays a critical role in its antioxidant activity. In addition, 18 potential antioxidants were screened out in CNJ by comparing the difference of it with and without DPPH reaction. They were identified mainly as catechin, ellagic acid, kajiichigoside F1, and their derivatives or isomers. With the further quantification of major found antioxidants, our results may provide some knowledge on predicting the antioxidative compounds of natural products.