Chinese indigenous pig breeds in the Taihu Lake region (TH) of Eastern China are well-recognized for their exceptional prolificacy. These breeds including Meishan (MS), Erhualian (EHL), Jiaxing Black (JXB), Fengjing (FJ), Shawutou (SWT), Mi (MI) and Hongdenglong (HDL). At present, these breeds are facing a great threaten of population decline, lineage admixture and inbreeding depression since Western commercial pigs have dominated Chinese pig industry. To provide better conservation schemes and identify candidate genes under selection for these breeds, we explored genome-wide SNP markers to unravel genetic variability and relatedness, population structure, historical admixture and genomic signatures of selection of 440 pigs representing the most comprehensive lineages of these breeds in TH in a context of 1228 pig from 45 Eurasian breeds. We showed that these breeds were more closely related among each other as compared to other Eurasian breeds, defining one of the main ancestral lineages of Chinese indigenous pigs. These breeds can be divided into two regional subgroups, one including JXB and FJ pigs, and the other comprising EHL, MI, HDL, MS and SWT pigs. In additional, HDL pigs were highly inbred, whereas EHL and MS pigs had more abundant genetic diversity. This is attributable to multiple conservation populations of the two breeds. Moreover, we identified a list of candidate genes for body size and prolificacy at the loci putatively under selection. our results would benefit the sustainable conservation of these valuable breeds and improve our understanding of the genetic mechanisms of body size and fecundity in pigs.