Abstract: Multicomponent high-entropy Cantor alloys have attracted extensive attention in the field of metallic material research due to their stable single-phase structures and excellent comprehensive properties. This review systematically investigates the influence of grain size on the tensile behavior and yield strength of Cantor alloys. Extensive experimental results reported in the literature indicate that when the grain size is in micron-scale range, yield strength of Cantor alloys follows the Hall-Petch relationship. However, when grain size is refined from micron-scale to submicron-scale, some alloys may exhibit a transition from continuous yielding to discontinuous yielding, accompanied by a positive deviation from the Hall-Petch slope. By analyzing the effect of factors such as yielding behavior, constituent components, and microalloying on Hall-Petch strengthening, this review summarizes alloying design and microstructural strategies for enhancing the Hall-Petch slope, which can provide guidance for developing next-generation ultra-high-strength Cantor alloys.