Objective: To evaluate the development and risk factors of white spot lesions (WSLs) in orthodontic patients with fixed appliances in a Chinese population. Methods: A total of 202 subjects participated in the cross-sectional study. Clinical examination of the state of the entire labial (buccal) enamel surface was conducted under artificial light using a clinical mirror and an explorer. A face-to-face interview was conducted through a structured questionnaire to collect a range of information, including demographic data, family income, level of education, toothbrushing frequency, fluoride toothpaste usage and the use of a professional toothbrush (V type). Results: WSLs appeared on 57.9% of the subjects after orthodontic treatment with fixed appliances; the mean tooth number of WSLs was 4.8. A higher prevalence was observed in subjects whose time of therapy was 17 months or longer (OR = 3.2, P 0.050), and who had modified their unhealthy dietary habits (OR = 3.7, P 0.001). Younger individuals or individuals who consumed food with sugar at least once a day during the course of their orthodontic treatment also exhibited a higher likelihood of experiencing WSLs. Conclusion: The prevalence of WSLs after orthodontic treatment with fixed appliances was relatively high in China. Clinicians should be aware of the risk factors of WSLs that may occur during the treatment period. Keywords: orthodontic treatment, risk factor, white spot lesions