Abstract: A computational method — microelement method which establishes the immediate relation between the microstructure and macroresponse in composite materials is discussed. The method, firstly, divides the composite structure into a set of macroelements, then analyzes the microstructure, and translates the variables of the microstructure into variables of nodes for calculation. In this method, any arbitrary pattern of microstructure and any tiny change will be reflected in macrovariables without increasing the degrees of freedom.