Abstract: Complex Ⅲ is an essential component of cellular respiration chain, and complex Ⅲ inhibitors are widely used for the control of fungal and oomycete diseases worldwide. According to the binding sites of the fungicides on the complex Ⅲ, they could be divided into three types, including QoI, QiI and QioI fungicides. Among them, the QoIs are the most common fungicides, which also suffers from heavy problem of fungicide resistance. This review summarizes the mode of actions and molecular resistance mechanisms of complex Ⅲ inhibitors, such as the G143A and F129L amino acid substitutions in the target protein cytochrome b (cyt b), the overexpression of alternative oxidase gene (AOX) in the alternative oxidation pathway, and the transport mechanism, aiming to provide a reference for the rational use of complex Ⅲ inhibitors.