Energy equivalent modulus medium of entrainment multiphase composite body is one of main methods, Those methods study frangible materials damage in micromechanics. Through studying the physical and mechanical process of microstructure varity, we can introduce some kind averaging method to find the material’s macroscopic property. It has not been studied as yet that we study entrainment composite body’s damage trough introducing continous field variable of every exponent tensor from macrophenomenology angle. This paper regards entrainment multiphase composite body as the micropolar medium of introducing inner structure. It provides analytic formula to describe equivalent modus of entrainment multiphase composite body damage, through the stress in micropolar theory of elasticity,couple-stresses tensor and Helmhoetz degrees of freedom density.