Abstract: The rule of power flow transmission with line force acting at an infinite plate is examined by effective mobility power flow method, and the theoretical formula of effective line mobility is given. Simulation is carried out to illuminate the power flow transmission property of effective line mobility. By comparing theoretical results with those calculated by numerical evaluation formula, suitable range of numerical evaluation formula is present. At last, power flow transmission law of a beam under line exciting is investigated, which is compared with that of an infinite plate under line exciting and displayed a little more power flow transferred in a plate than in a beam. Study shows much flexible and more validity by using of theoretical formula of effective line mobility in studying the power flow transmission between structures.