Fertility support policies are essential for addressing low fertility rates, and it is crucial to promptly evaluate their effects on fertility. Based on the data from a specialized survey in China, this study adopts the Logit model to examine the impact of expected policy effects on fertility plans across various parental statuses and their mechanisms. The results show that positive expectations of policy effects significantly promote fertility plans. Paid parental leave and universal childcare are particularly effective for married but childless individuals. Paid parental leave and childcare subsidies also support fertility plans among parents with one child. The impacts of expected policy effects are heterogeneous across marital statuses and socioeconomic backgrounds. A positive fertility concept positively moderates the impact of policy effects. Favorable expectations for multiple policies can generate synergistic effects in promoting fertility plans. The findings suggest that we should publicize fertility support policies, enhance policy targeting, highlight the power of culture, and improve policy synergy.