Abstract Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O high entropy oxide (HEO) with outstanding cycling stability and high capacity retention indicates it is a promising anode material for rechargeable lithium‐ion batteries. Rock salt HEO nanofiber has been prepared by electrospinning method. Polyacrylonitrile polymer facilitates the formation of nanowire morphology. The effect of calcination temperature on the phase composition and microstructure evolutions has been investigated. Pure rock salt phase can be obtained after firing at 850°C for 2 min. Calcination at higher temperature than 850°C will break the fiber into short segments and lead to the growth of grain. A reversible capacity of 365 mAh g −1 was achieved after 300 cycles at .2 A·g −1 .