In this study, the microstructures of the directionally solidified FCC/B₂ dual-phase high-entropy alloy were tailored based on different heat treatment processes to improve the mechanical properties in a wide temperature range. The microstructure evolution mechanism under different heat treatment regimes was clarified, and the influence of microstructures on the mechanical properties of the alloy was analyzed. The results show that high-density near spherical L1₂ precipitates can be obtained in the FCC matrix, while lath-like L1₂ precipitates can be obtained in the B₂ phase after solution treatment followed by double aging at high-temperature 800 ℃ and low-temperature 650 ℃. High-density precipitates effectively strengthen the alloy, and the L1₂ phase can promote dislocation movement in the B₂ phase, which is beneficial to improve the plasticity of the alloy at the same time. Compared to the as-cast sample, the comprehensive hightemperature mechanical properties of the alloy after heat treatment are improved.