The experimental study utilised a pre-test, post-test, and after-test design to assess the impact of a peer instruction teaching method on enhancing the subjective well-being of students in a seniors' university in China. A total of 118 senior students were randomly assigned to either an experimental group or a control group. Both groups received instruction from the same educator, with the experimental group being taught through the peer instruction method, while the control group experienced a traditional teaching method. After intervals of six months and twelve months, the study reassessed the subjective well-being (SWB) of the participants, referred to as the post-test and after-test, respectively. Additionally, approximately 16 students from the experimental group were interviewed to validate the findings obtained from the questionnaire. The analysis indicated that the mean scores associated with subjective well-being in the experimental group were significantly higher than those in the control group during both the post-test and the after-test. Conversely, the mean scores negatively correlated with participant's subjective well-being in the experimental group were significantly lower than those in the control group in both the post-test and the after-test. The findings of this study suggest that the peer instruction teaching method is effective in promoting the subjective well-being of senior learners.