Abstract: In order to investigate the epidemic situation of porcine epidemic diarrhea（PED） in large-scale pig farms in North China from 2017 to 2020, the experiment collected 4 030 samples of diarrhea piglets from 218 large-scale pig farms in five provinces（autonomous regions or municipalities） of Hebei, Shanxi, Inner Mongolia, Beijing and Tianjin, and RT-PCR detection was carried out. Part of the S1 gene fragment of Porcine epidemic diarrhea virus（PEDV）-positive samples was amplified and sequenced; homology analysis was carried out between the sequencing results and domestic and foreign reference strains and a genetic evolutionary tree was constructed. The results show that PED could occur all year round, and it occured more frequently in the first quarter and the fourth quarter. From 2017 to 2020, the PEDV nucleic acid positive rates of the samples were 20.21%, 15.28%, 10.88%, and 18.80%, respectively, showing a downward trend year by year, but slightly increased in 2020; the PEDV nucleic acid positive rates of pig farms were 34.78%, 28.00%, 25.00% and 22.73% respectively, which also showed a downward trend year by year. The nucleotide similarity of the sequencing isdate with gene GⅠ strain Vaccine CV777 was 87.9%-91.9%. The nucleotide similarity with the GⅡ genotype represented by AJ1102 was 95.7%-99.0%.31 gene sequences were obtained by sequencing belonged to GⅡ genotype strains, of which 20 strains belonged to GⅡa genotype, 8 strains belonged to GⅡb genotype, and the remaining 3 strains belonged to GⅡc genotype. The results suggested that the incidence of PED in North China was generally decreasing year by year from 2017 to 2020, and all the PEDV epidemic strains belonged to the GⅡ genotype.