Abstract Historically, informal adoption has been a prevalent Chinese social phenomenon that has altered typical family structures and the lives of children. Due to ambiguous definitions and the scarcity of data on informal adoption, the patterns and processes of informal adoption are not well understood. Therefore, in this study, data from commonwealth websites were used to explore the temporal and spatial patterns and network evolution of informal adoption from 1924 to 2018. The results indicate that severe famine and birth control campaigns increased the number of informal adoptions. Son preference was highlighted during the strict implementation of the one-child policy. From a spatial perspective, the data are distributed in provinces and zones with higher population densities. Major cities also play a key role in information transfer. We expect the findings to provide basic knowledge on informal adoption in China and serve as a reference for the protection of children’s rights.