China banned colistin as growth promoter for animals in the year of 2017. A decrease of colistin-resistant Escherichia coli(COREC) and mcr-1-positive Escherichia coli(MCRPEC) were observed in livestock (pigs and chickens) and humans after the ban policy. However, the prevalence of COREC among Chinese companion animals after the ban policy has not been investigated. Here, we recovered 771 E. coliisolates from the China Antimicrobial Resistance Surveillance Network for Pets (CARPet) surveillance system (19 provinces/municipalities) from 2018 to 2021. We identified 12 COREC from eight dogs and four cats, among which one feline and three canine isolates were MCRPEC. The prevalence of COREC and MCRPEC in pets from 2018–2021 (1.1%–2.2% and 0.8%–1.1%) were lower than those from 2012–2016 (7.1%–17.8% and 6.1%–14.3%). The phylogenetic analysis revealed that the four MCRPEC isolates displayed genetic diversity, while one canine isolate exhibited only 26 SNPs difference with one human MCRPEC isolate in the same city, suggesting the exchange of MCRPEC isolates between companion animals and humans. In three MCRPEC isolates, mcr-1was located on an IncI2 plasmid, which exhibited 99.5%–99.9% nucleotide sequence identity with plasmid pHNSD133-MCR from E. coliof chicken origin. In the remaining MCRPEC, mcr-1was chromosomally located flanked by intact ISApl1elements forming a unit of ISApl1-mcr-1-pap2-ISApl1. Despite the low prevalence of COREC and MCRPEC observed in companion animals after the ban policy, the association of pet-derived MCRPEC and mcr-carrying plasmids with those from humans and farm animals suggest that annual surveillance of colistin resistance in bacteria of pet origin is essential.