Objective: To explore and study the effect of liquid nitrogen freezing combined with photodynamic therapy on the treatment of solar keratosis. Methods: 86 patients with solar keratosis who were treated in the dermatology outpatient clinic of our hospital from January 2022 to January 2024 were selected as research subjects. According to the treatment method, it was divided into combined treatment group (n=40) and liquid nitrogen freezing group (n=40). The combined treatment group used liquid nitrogen freezing combined with 5-aminoketone glutanate photodynamic therapy for treatment of the study subjects, and the liquid nitrogen freezing group only used single liquid nitrogen cryotherapy for the study subjects. Then compare the clinical efficacy of the two groups of patients and the incidence of adverse reactions. Results: The total treatment efficiency of patients in the combined treatment group was higher than that of the liquid nitrogen freezing group, and the difference was statistically significant (P<0.05). In the incidence of adverse reactions, the combined treatment group was 27.5% (11/40) and the liquid nitrogen cryotherapy group was 70.0% (28/40). The difference between the two groups was statistically significant (P < 0.05). The incidence of pigmentation in the liquid nitrogen freezing group was 62.5% (25/40), significantly higher than that of 25.0% (10/40) in the combined treatment group, and the difference was statistically significant (P < 0.05); the incidence of scarring in the liquid nitrogen freezing group was 7.5% (3/40), and the scarring in the combined treatment group The incidence rate is 2.5% (1/40), and the difference is not statistically significant (P > 0.05). Conclusion: Compared with the single use of liquid nitrogen cryotherapy, liquid nitrogen cryotherapy combined with photodynamic therapy has better clinical efficacy and lower incidence of adverse reactions.