Using the 2018 CHARLS data, this paper empirically analyze the impact of income on the level of depression in elderly people. Research has found that as income increases, the level of mental depression in the elderly significantly decreases, thereby improving the mental health level of the elderly population. The multiple threshold regression estimation results indicate that income has a significant dual threshold effect on the level of depression 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 coefficient changes. Finally, this paper suggests to improve the level of security for the elderly and share the fruits of economic and social development; developing human resources for the young elderly and ensuring their reemployment; encourage elderly people to participate in social activities and provide non-cash social support.