The vertical and horizontal transmission of resistance genes in the environment makes antibiotic resistance as a global problem threatening human and animal health. Animal food is an indispensable part of human diet. Due to the overuse and abuse of antibiotics, antibiotic resistance genes in animal farms should be concerned. In this paper, the source, transmission routes and influencing factors of antibiotic resistance genes in animal farms, as well as risk assessment and control techniques are described, and suggestions on the future direction of researches on antibiotic resistance genes are proposed.