Recently, the ocean acoustic tomography (OAT) has been used for investigation into the phenomenon of global warming.It has become seroius problem in OAT to discriminate refracted and bottom-reflected pulses in received pulse series. The characteristics of sound propagation for bottome-reflected pulse are analyzed in time-domain on the ocean model which consisted of an isovelocity water layer over an isovelocity halfspace bottom (Pekeris Waveguide). The effects of sound-speed in a seabottom, number of additional modes and hydrophone depths are investigated. We comfirm that the bottom-reflected pulses have the same waveform as refracted pulses which consisted of three sets of pulses when the source and hydorophone are set at the same depth, and that the characteristics of sound propagation is effected by the oceanic conditions very much. It is very important in OAT investigation to understand exactly the difference between refracted and bottom-reflected pulses.