Objective: To observe clinical efficacy of different concentrations 5-aminolevulinic acid photodynamic therapy (5-ALA-PDT) in grade I-II cervical intraepithelial neoplasia (CIN) combined with human papillomavirus (HPV) infection. Methods: A total of 104 patients with grade I-II CIN and HPV infection were enrolled as the research objects. According to different interventions, they were divided into high-concentration group (20% 5-ALA-PDT) and low-concentration group (10% 5-ALA-PDT), 52 cases in each group. Both groups were treated for 6 months. The efficacy, negative conversion rate of HPV, cervical function (cervical canal stenosis, abnormality of cervical mucus secretion, cervical adhesion) and adverse reactions (scar formation, infection, pain, increased vaginal discharge, lower abdominal distension) were compared between the two groups. Results: After 6 months of treatment, there was no significant difference in total response rate between patients with grade I CIN and those with grade II CIN in high-concentration group and low-concentration group (P>0.05), but there were significant differences in total response rate between high-concentration treatment and low-concentration treatment for patients with grade II CIN (P<0.05). In high-concentration group, there was no significant difference in 6-month negative conversion rate of HPV between grade I CIN and grade II CIN (P>0.05). In low-concentration group, 6-month negative conversion rate of HPV in grade I CIN was higher than that in grade II CIN (P<0.05). For patients with grade I CIN, there was no significant difference in negative conversion rate of HPV between high-concentration treatment and low-concentration treatment (P >0.05). For patients with grade II CIN, negative conversion rate of HPV after high-concentration treatment for 6 months was higher than that after low-concentration treatment (P <0.05). After 6 months of treatment, there was no significant difference in the incidence of cervical canal stenosis, abnormal cervical mucus secretion and cervical adhesion between high-concentration group and low-concentration group (P>0.05). The incidence of adverse reactions in high-concentration group was higher than that in low-concentration group (P<0.05). Conclusion: The efficacy of high-concentration 5-ALA-PDT is significant in grade II CIN combined with HPV infection, and negative conversion rate of HPV is considerable. However, the effect of high-concentration 5-ALA-PDT is few in improving efficacy and negative conversion rate of HPV in patients with grade I CIN and HPV infection, and it will instead increase the incidence of adverse reactions.