Competition and cooperation are fundamental to the stability and evolution of ecological communities. The human gut microbiota, a dense and complex microbial ecosystem, plays a critical role in the host's health and disease, with competitive interactions being particularly significant. As a dominant and extensively studied group in the human gut, Bacteroidales serves as a successful model system for understanding these intricate dynamic processes. This review summarizes recent advances in our understanding of the intricate antagonism mechanisms among gut Bacteroidales at the biochemical or molecular-genetic levels, focusing on interference and exploitation competition. We also discuss unresolved questions and suggest strategies for studying the competitive mechanisms of Bacteroidales. The review presented here offers valuable insights into the molecular basis of bacterial antagonism in the human gut and may inform strategies for manipulating the microbiome to benefit human health.