Loneliness is prevalent and severe among adolescents, indicating the need for a reliable, valid, and concise instrument for detecting adolescent loneliness. This study aims to examine the psychometric properties of the Chinese version of the short-form UCLA Loneliness Scale (ULS-8) among Chinese adolescents.Computer-assisted self-interviewing was used to complete the questionnaire among 3480 junior or senior high school students aged 10 to 19 years. Construct validity was assessed using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). To test the concurrent validity and convergent validity of the scale, a single loneliness item and variables such as depression, suicidal ideation, and quality of interpersonal relationships were used. For reliability, Cronbach alpha and test-retest correlation were computed.Construct validity and internal consistency showed that the ULS-6, which excluded 2 reverse-scored items from the ULS-8, had stronger psychometric properties than the ULS-8. The convergent validity and concurrent validity were also supported by the study results. The overall Cronbach α of the ULS-6 was 0.878 and the test-retest reliability coefficient was 0.663.The ULS-6 showed satisfactory reliability and validity in this study, suggesting that this instrument can be used in the measurement of loneliness among Chinese adolescents.