The development and phase formation criteria of high entropy alloy (HEAs) are described briefly. A new alloy design form is proposed in view of the big data system of high entropy alloy, and a new high entropy alloy is designed and studied. The result shows that the design form, AxByC(100-a-b-x-y)DaEb, is more in line with the requirements of the big data system compared with the previous alloy forms such as AxBCDE. The proposed design method can screen the expected alloy composition from the big data system of high entropy alloy rapidly and visually. The designed high entropy alloy, AlCoCrFeMo0.05Ni2, agrees with the target alloy, and has a great application prospect below 700 ℃.