High entropy alloy (HEA) is an advanced alloy material, which has a wide application prospect due to its excellent properties. However, the material removal mechanism and change rule of grinding force of HEA in the grinding process have seldom been studied. The main work of this paper is that the material removal mechanism of the FeCoNiCrMo0.1 HEA is obtained by analyzing grinding debris and subsurface microstructure after grinding, the theoretical grinding force model of HEAs in plane grinding process is established on the basis of the force of a single abrasive grain, and the experimental verification is performed. According to the experimental results, the influences of different grinding parameters on grinding force are discussed, the influences of different types of grinding wheels on grinding force are analyzed, and the grinding forces generated by grinding different FeCoNiCr HEAs are compared. The results indicate that the material removal mechanism of FeCoNiCrMo0.1 HEA is the plastic removal. With the increase of grinding speed and the decrease of grinding depth and feed speed, both normal and tangential grinding forces decrease. Under the same grinding parameters, the grinding force produced by electroplated CBN grinding wheel is greater, followed by resin-bonded CBN grinding wheel and vitrified CBN grinding wheel. The grinding force produced by grinding FeCoNiCrAl0.1 HEA is lower than that produced by grinding FeCoNiCrMo0.1 HEA under the same grinding conditions. The calculated value of grinding force model is consistent with the experimental value, which can scientifically reflect the variation law of HEA grinding force.