Studies have found that adolescents' subjective well-being (SWB) shows a downward trend with age. The improvement of adolescents' SWB is therefore an urgent problem. According to previous studies, altruism may be an effective way to improve adolescents' SWB. We conducted an Integrative Educational Intervention of Altruism (IEIA) for the first time to determine whether altruism intervention can effectively improve adolescents' SWB. We conducted an IEIA on adolescents in an experimental group for 14 weeks using pre- and post-test experimental designs with peer groups. The participants were randomly recruited from a junior high school in East China and included 280 Grade 8 students (138 boys and 142 girls; mean age: 14.53 years). Before and after the experiment, the adolescents completed measures of SWB using the Multidimensional Students' Life Satisfaction Scale and Happiness Scale. From the pretest, we found no significant differences in friendship, academic, freedom, school and social satisfaction or positive emotions between the control and experimental groups. However, in the post-test, the life satisfaction and positive emotions of the experimental group were rated significantly higher than those of the control group. These results show that experimental intervention can effectively improve adolescents' life satisfaction and positive emotions. Altruistic intervention was identified as an effective way to improve adolescents' SWB. It is thus necessary to cultivate altruistic environments, to enrich altruistic education programs, and to carry out voluntary services for the benefit of the public. Altruistic adolescents themselves may benefit when helping others. Copyright © 2020 The Foundation for Professionals in Services for Adolescents. All rights reserved.