Abstract: The Dongji black pig is a new group of black pigs found in the Northeastern part of China. The purpose of this study was to understand the population structure and genetic diversity of Dongji black pigs, so as to better protect and utilize the genetic resources of Dongji black pigs. The genetic diversity, genetic relationship and family structure of 426 Dongji black pigs were studied by 50k SNP chip. At the same time, the data of 20 Large white pigs and 20 Min pigs were added together for principal component analysis（PCA）. The results showed that 47 389 SNPs out of 57 466 SNPs in Dongji black pigs passed the quality inspection. The results of PCA showed that the three populations were clustered separately, and the Dongji black pig was clearly distinguished from the other two pig breeds, and some individuals in the Dongji black pig population were closely related to each other, the genetic distance of identity by state（IBS） was 0.097 7-0.358 9, and the average value was 0.275 2,runs of homozygosity（ROH） analysis showed that the average ROH of this population was 317.3 Mb. It was mainly distributed in 200-300 Mb, and the average inbreeding coefficient（FROH） of the population was 0.133, indicating that there was inbreeding. According to the results of genomic genetic relationship analysis and cluster analysis, the Dongji black pig population could be divided into 15 families. The comprehensive analysis showed that the Dongi black pig population was rich in genetic diversity and unique breeds, but there was inbreeding, and it was suggested to introduce new bloodlines to prevent the loss of genetic diversity.