At present, the strength and toughening degree of the multi-principal element high entropy alloy are not high, and the plastic deformation capacity is poor. In order to solve this problem, the structure and mechanical properties of the multi-element high entropy alloy were studied. The micro-structure and strengthening mechanism of the alloy were studied. By establishing a reliable random solid solution model and using the first principle to calculate the phase structure, thermodynamics, and elastic properties of the alloy, theoretical guidance is provided for the design and development of new high entropy alloy. The high entropy alloy system with high specific strength and high tensile plasticity was prepared, and its strengthening and toughening mechanism was studied. The experimental results show that with the increase of Zr content, the fracture strength of multi-component high entropy alloy first increases and then decreases. When it reaches a fixed value, the comprehensive mechanical properties of the alloy are the best. Compared with the two literature methods, the tensile strength of this method is 250 MPa, and the work hardening after yielding makes the alloy have higher strength and better plastic deformation ability.