This study aimed to analyze the impact of different additions (0–1.25%) of yam bean powder (YBP) on myofibrillar protein (MP) gel characteristics such as the structure, water-holding capacity (WHC), chemical interaction strength of grass carp MP, and texture. The results showed that the YBP exhibited a strong water absorption capacity and filled in the protein heat-induced polymerization gel network well, which enabled the gel network to capture and retain water effectively, resulting in MP gels containing YBP with excellent WHC and gel strength (0.75%). In addition, YBP induced the formation of hydrogen and disulfide bonds in proteins and inhibited the conversion of α-helices to β-sheets and β-turn structures, facilitating the formation of high-strength gel networks (p< 0.05). In conclusion, YBP can significantly improve the thermally induced gelling properties of grass carp MP. In particular, the addition of 0.75% YBP had the best effect in terms of filling the gel network of grass carp MP, resulting in the formation of a continuous and dense protein network, leading to the composite gel with the best WHC and texture.