The problem of bimodulous beam with equal height and variable cross sections impacted, was stadied, by heavy weight. The impacted bimodulous beam of equal height and variable cross sections was simplified as a elastic system with single degree of freedom which composed by a concentrated mass and a spring without weight, thus the problem of beam impacted by heavy weight was simplified as single degree of freedom elastic system with concentrated mass impacted by heavy weight, then function expressions for factor of dynamic load and impact time were derived by dynamic equation, the defects of the energy method, which can only give the maximum factor of dynamic load, was overcome. The analysis of examples indicated that formulas for the maximum factor of dynamic load which given by related literatures is only a special case of function formula for factor of dynamic load that obtained by dynamic equations. The problem of bimodulous beam with equal height and variable cross sections impacted by heavy weight, in which have a larger difference elastic moduli in tension and compression, can not be treated simply as the problem of single-modulus beam with equal height and variable cross sections impacted by heavy weight, the influence of difference elastic moduli in tension and compression must be taken into consideration.