A time-domain reflective beam propagation method (TD-RBPM) is presented for the analysis of optical pulse propagation and reflection in waveguide structures with multiple discontinuities. By utilizing an implicit scheme, the method allows relatively large time steps and, therefore, is highly efficient. The accuracy of the method is verified by simulating a time-domain Gaussian pulse reflected and transmitted from a multiple period grating and a four-layer antireflection coating structure.