High entropy alloys, a new type of hot-research alloy, have received extensive attention in the material industry. Taking equal atomic ratio CoCrFeNiMn as the prototype, numerous fcc-structure high-entropy alloys with excellent mechanical properties have been reported. Recently eutectic high-entropy alloys have attracted more and more attention of scientific researchers due to their excellent casting properties and comprehensive mechanical properties. In this paper, we selecte the CoCrFeNiNbx alloy system, focus on precipitation-strengthened high-entropy alloys and eutectic high-entropy alloys, and summarize the current research progress from the aspects of composition design, microstructure evolution, mechanical properties and strengthening and toughening mechanism. Finally, we analyze the shortcomings of current research and point out the direction of future research.