With rapid development and modernization of today's society, the resource inequality between rural and urban areas has enlarged, especially regarding adolescents' mental health education. In order to provide alternative to adolescents with limited resources, this study targets test anxiety as example, aiming to explore the effectiveness of online mindfulness training in alleviating students' test anxiety through a quasi-experiment. This study recruited youths from 12 to 18 years old and used their pre-test/post-test data on 186 trained participants (M[subscript age ]= 14.85, 57.5% male) and 217 propensity-score matched controls (M[subscript age ] = 15.35, 53% male). After careful analysis, the results proved the effectiveness of online mindfulness training in reducing test anxiety and showed that the online training was more beneficial for students with serious interpersonal problems. This study further provided implications for the use of technology in mental health education, promoting the care of psychological well-being in rural areas.