A feedback resource determining method and apparatus is applied to systems such as an internet of vehicles, V2X, and V2V. The method includes obtaining a first parameter, where the first parameter is related to a cast type and a hybrid automatic repeat request HARQ feedback manner, the cast type includes unicast and multicast, and the HARQ feedback manner corresponds to the cast type; and determining a physical sidelink feedback channel PSFCH based on the first parameter. According to the feedback resource determining method and apparatus provided, PSFCHs of different sizes are allocated for different cast types and HARQ feedback manners. This improves resource utilization.