Abstract: On the basis of thermoelasticity theory, an equivalent circuit model of laser-generated ultrasound has been proposed. With this model, lase-heated region is separated from surrounding medium and described as a three-ported electrical circuit which demonstrates the direct conversion between thermal energy and elastic energy, while contacting with external transporting medium in the form of radiation impedance. As the circuit is derived fron single frequency excitation, arbitrary temporal response can be calculated by means of IFFT algorithm. In this paper, three kinds of typical heated regions are considered in the case of circular plate, cylinder and sphere. Their laser pulse responses are calculated and diagramed respectively. It is shown that results agree well with previous reports.