To analyze the application effect of external application of platelet-rich plasma in the treatrnent of deep second-degree burn wounds. Methods A total of 94 patients with deep second-degree burns admitted to the Third People's Hospital of Linyi City from May 2021 to May 2023 were selected as the research objects. According to the random number table method, they were divided into control group and observation group, with 47 patients in each group. The control group was treated with sulfadiazine silver ointment for external application, and the observation group was treated with platelet-rich plasma for external application. The wound healing, dressing exudate and dressing change, positive rate of peri-wound inflammatory reaction and adverse reactions were compared between the two groups. Results The wound healing rate of the observation group was higher than that of the control group on the 11th, 14th and 17th day, and the wound healing time was shorter than that of the control group,and the differences were statistically significant (P <0.05). The number of layers of wet gauze, the number of dressing changes, and the number of inner gauze replacements in the observation group were less than those in the control group, and the differences were statistically significant (P <0.05). The positive rate of peri-wound inflammatory reaction in the observation group was 4.26%, which was lower than 17.02% in the control group, and the difference was statistically significant (P <0.05). No adverse reactions occurred during the treatment in the two groups. Conclusion External application of platelet-rich plasma can promote wound healing in patients with deep second-degree burns, shorten wound healing time, reduce the number of dressing changes, and reduce the risk of inflammatory reactions. It is safe and worthy of clinical application.