Using the 2018 CHARLS data，this paper empirically analyzes the impact of income on the depression level of elderly people. Research has found that as income increases，the level of depression among the elderly significantly decreases， thereby improving their mental health level. The multiple - threshold regression estimation results indicate that income has a dual threshold effect on the depression level in elderly people. The effect of income is non-linear，and as the income level increases，the positive impact of income on the mental health of the elderly decreases. Further research shows that urban and male elderly people have higher income thresholds，while rural and male elderly people exhibit more complex non-linear changes. Finally， this paper suggests improving the security level for the elderly and sharing the fruits of economic and social development；developing human resources for the young elderly and ensuring their re-employment；encouraging elderly people to participate in social activities and providing non-cash social support.