Objective To investigate the difference between oral isotretinoin capsules and photodynamic therapy in the treatment of facial acne vulgaris. Methods A total of 68 patients with facial acne vulgaris in our hospital from May 2020 to May 2021 were selected. According to different medication methods, 34 cases treated with isotretinoin capsules were set as the oral group, and 34 cases treated with photodynamic therapy were set as the photodynamic group. The GAGS scores, efficacy levels and adverse reactions of the two groups at 4, 8 and 12 weeks after treatment were compared. Results The GAGS score of photodynamic group was lower than that of oral group at 4 and 8 weeks of treatment (P＜0.05). There was no significant difference in the GAGS scores between the two groups at the end of the 12th week of treatment (P＞0.05). The effective rates of photodynamic group at 4,8,12 weeks were 58.82%, 67.65%, 73.53%, which were higher than those 32.35%, 38.24%, 44.12% of oral group (P＜0.05). The incidence of adverse reactions in photodynamic group was lower than that in oral group (P＜0.05). Conclusion For patients with chronic acne vulgaris, photodynamic therapy has better short-term effect than oral treatment.