Multi-element alloys (e.g., non-equiatomic FeMnCoCr alloys) have attracted extensive attention from researchers due to the breaking of the strengthen-ductility tradeoff relationship. Plenty of work has been conducted to investigate the ingredient-dependent deformation mechanism in these alloys in experiments. However, the atomic simulations on such parameter-related mechanisms are greatly limited with the lack of the related interatomic potentials. In this work, two interatomic potentials are developed within the embedded atom method (EAM) framework for Fe80−xMnxCo10Cr10 high-entropy alloys. The tunability of the cohesive energy-related martensitic transformation (MT) mechanism was comprehensively investigated using molecular dynamics (MD) through a series of unilateral crack configurations with different twin boundary spacings (TBs). It is noted that the main deformation mechanism around the crack tip is transformed from a martensitic transformation to dislocation activities (dislocation or twin) with the variation of different cohesive energies between face-centered cubic (fcc) and hexagonal close-packed (hcp) phases. Additionally, the introduction of twin boundaries significantly enhances the strength and toughness of the alloys. The newly developed interatomic potentials are expected to provide theoretical support for the related simulations, focusing the martensitic transformation mechanism on high-entropy alloys.