Paraquat (1, 1'-dimethyl-4, 4'-bipyridylium) is a non-selective herbicide widely used in the world more than 35 years. The action mechanism of this herbicide to kill plants is an inhibition of electron transport in photosystem Ⅰ, which also results in the formation of oxidative stress environment due to a large production of reactive oxygen species. Since the long-term application of paraquat, herbicide resistance in weed plants has been reported and paid more attentions. In this article, physiological mechanisms of paraquat resistance commonly found in weed plants and microbes, including uptake, translocation, and metabolism of paraquat, as well as antioxidative system to remove free radicals generated by paraquat radical, are reviewed and discussed.