In view of the advantages of the combination of traditional Chinese medicine (TCM) in the treatment of cerebral ischemia, we studied the differences in the efficacy and mechanism between the preparation combination and the component combination in order to explore the two herb combination strategy to treat injured PC12 cells. Cobalt chloride (CoCl2) combined with a glucose-free medium was employed to induce oxidative damage of PC12 cells. Then, the optimal combination of Astragalus mongholicus (Ast) and Erigeron breviscapus (Eri) injection was selected and combined following uniform design methods after screening their safe and effective concentration on PC12 cells. Further, the component combination screened comprises 10 µM astragaloside A, 40 µM scutellarin, and 75 µM chlorogenic acid in two herbs. Then, MTT, Annexin V-FITC/PI, immunofluorescence, and Western blot analysis were used to evaluate the efficacy and mechanism of the preparation combination and the component combination on injured PC12 cells. The results showed that the optimal preparation combination for cell pro-survival was Ast injection and Eri capsule with a concentration of 6:1.8 (µM). The component combination (10 µM astragaloside A, 40 µM scutellarin, and 75 µM chlorogenic acid) was more effective than the preparation combination. Both combinations remarkably reduced apoptotic rate, the fluorescence intensity of caspase-3, and intracellular reactive oxygen species (ROS) level; meanwhile, they upregulated the expression levels of p-Akt/Akt, Bcl-2/Bax, and Nrf2. These effects were more evident in the component combination. In conclusion, both combinations can inhibit the injury induced by CoCl2 combined with a glucose-free medium on PC12 cells, thus promoting cell survival. However, the efficiency of the component combination over the preparation combination may be due to its stronger regulation of the PI3K/Akt/Nrf2 signaling pathway related to oxidative stress and apoptosis.