Abstract: At present, the research on high entropy alloys at home and abroad mainly focuses on the preparation process, microstructure characterization and physicochemical properties.With the rapid development and wide application of computer technology, the phase diagram calculation method is also booming in the field of materials science.The thermodynamics and solidification characteristics of AlFeCoCrNiMo_x high entropy alloy were simulated by phase diagram method.The relationship between temperature and phase content, element atomic content in each phase, and the relationship between solid fraction and element atomic content in each phase were analyzed.The simulation results show that the content of alloy phase and element atom in each phase changes with temperature. In the relationship curve between temperature and phase content, with the content of Mo element increasing, the σ atomic content and MU phase of alloy increase. At the same time, the γ phase and BCC content decrease, then, the strength, hardness, plasticity and toughness of the alloy changes. When the solid fraction tends to 1.0 (i.e.fully solidified state), the content of Mo in liquid phase increases and that of Ni decreases obviously, while that of Ni in NiAl phase decreases obviously with the increase of Co content, the increase of Mo and Ni in γ phase decrease obviously, while the increase of Co in BCC phase decreases obviously with the increase of Mo.The Cr element is main phase in σ phase, while the content of Mo element in the σ phase increases gradually as the solid fraction approaches 1.0.