To explore the regulatory effects of cryptotanshinone on oxidative stress, proliferation, apoptosis and c-Jun N-terminal kinase (JNK) pathway in human lens epithelial cells (HLE-B3) induced by hydrogen peroxide (H₂O₂). HLE-B3 cell line was cultured in vitro, and HLE-B3 was treated with 100 μmol/L H₂O₂ for 24 h, and then treated with different concentrations of cryptotanshinone (2.5, 5.0, 10.0 μmol/L) respectively. The optimal concentration of cryptotanshinone was selected according to the results of HLE-B3 cell viability. Then the cells were divided into control group (no intervention), H₂O₂ group (100 μmol/L H₂O₂ treatment), cryptotanshinone group (100 μmol/L H₂O₂+10.0 μmol/L cryptotanshinone treatment), and SP 600125 group (100 μmol/L H₂O₂+20 μmol/L JNK signaling pathway inhibitor SP 600125), inhibitor group (100 μmol/L H₂O₂+10.0 μmol/L cryptotanshinone+20 μmol/L SP 600125) and activator group (100 μmol/L H₂O₂+10.0 μmol/L cryptotanshinone+2 mg/L anisomycin, JNK signaling pathway activator), and drug interventions were performed for 24 hours. The contents of superoxide dismutase (SOD) and malonaldehyde (MDA) were detected by kit method. 5-ethynyl-2′-deoxyuridine (EdU) assay was used to detect cell proliferation. Hoechst 33258 staining kit was used to detect cell apoptosis. Western blot (WB) was used to detect the expression of CyclinD1, Caspase-3 and JNK pathway-related proteins. According to the results of HLE-B3 cell viability, 10.0 μmol/L cryptotanshinone was selected for subsequent experiments. SOD level, proliferation rate and CyclinD1 protein level in H₂O₂ group were lower than those in control group (P<0.05), MDA level, apoptosis rate, Caspase-3 and phosphorylation (p) -JNK protein levels were higher than those in control group (P<0.05). Cryptotanshinone group and SP 600125 group significantly inhibited the above effects of H₂O₂ on HLE-B3 cells (P<0.05). Compared with cryptotanshinone group, inhibitor group enhanced the effect of cryptotanshinone on H₂O₂-induced HLE-B3 cells (P<0.05), and activator group weakened the effect of cryptotanshinone on H₂O₂-induced HLE-B3 cells (P<0.05). Cryptotanshinone inhibits H₂O₂-induced oxidative stress and apoptosis of HLE-B3 by inhibiting JNK signaling pathway, and promotes its proliferation.