A study of equivalent circuit model of quantum well lasers derived from quantum well rate equation has been carried out, Pulse response simulation results obtained from a SPICE simulator indicates that various modulation properties, e.g., turn-on delay, relaxation oscillation frequency, and on/off aspect ratio, have a substantially different behavior than those of DH lasers, This model offers a fundamental building block for the simulation of the over all signal transmission when using quantum-well lasers as a light source.