China's fertility transition process is characterized by a regionally progressive pattern. The process of fertility transition exhibits both temporal and spatial diffusion phenomena, with migrant flows serving as a crucial channel for fertility diffusion. Using data from the Life History Survey of the China Health and Retirement Longitudinal Study (CHARLS) 2014 and provincial fertility data, this paper examines the relationship between fertility environment changes resulting from inter-provincial migration and women's number of children ever born and reproductive behaviors. The analysis reveals that migration experiences from high-fertility regions to low-fertility regions reduce the lifetime number of children. Migration experiences in relatively low-fertility regions significantly decrease the probability of giving birth. This indicates that changes in the fertility environment serve as a critical pathway through which migration experiences shape reproductive behaviors. In the context of large-scale population migration from rural to urban areas and from central and western to eastern regions, this study provides a micro-level explanation for the diffusion phenomena observed in China's fertility level changes.