The purpose of this study was to investigate how school art therapy using positive psychology affects high school students happiness and school life satisfaction. Thirty-three second graders from B Girls High School at A city were divided into the experimental group, comparative group, and control group, and pre-post experimental designs were conducted. The experimental group participated in school art therapy using positive psychology, the comparative group participated in only psychology theory classes, and the control group did not participated in any treatment. As a result of the analysis, in the pre- and post-test of happiness, the experimental group showed a significant increase in the total score, and among the sub-factors, there was a significant increase in passionate-participating life and meaningful life. In the pre- and post-test of school life satisfaction, there was no significant difference in the experimental group. The comparative group showed no significant difference in the total score, but among the sub-factors, the teacher area showed a significant decline. The control group showed a significant decline in the total score, and among the sub-factors, the overall school life and the teacher area showed significant declines. Collectively, the results showed that school art therapy using positive psychology was effective in improving high school students happiness and maintaining school life satisfaction despite unstable conditions caused by COVID-19. Based on these research results, the significance and limitations of this study were discussed.