Abstract: FeCoCrNiAl high entropy alloy coating was prepared on 45 steel through plasma cladding. The influence of cladding current and plasma gas velocity on the microstructure and porosity of the coating was studied.The results show that, when the cladding current is 180 A, the plasma gas velocity is 2.5 L/min, and the cladding rate is 100 cm/min, the prepared FeCoCrNiAl alloy coating binds well with the substrate, has no crack and the lowest porosity of 0.0276%. The high entropy effect of FeCoCrNiAl alloy coating by this process is significant. However, the microstructure of the coating not only has a BCC phase but also has some FCC phases including Fe-Cr phase, Ni-Co phase, Al-rich phase, Ni-rich phase. The Vickers hardness of the FeCoCrNiAl high entropy alloy coating is 500 HV, which is twice as much as that of 45 steel substrate.