Abstract: In order to study the problem that Ultra-Wideband (UWB)system can distinguish the multipath components and indiscernibility more carrying signals, Rake receiver diversity technology is used. In the signal transmitter, Binary Phase Shift Keying (BPSK) and Pulse Position Modulation (PPM) modulation method are used respectively. From the analytic expression of these two kinds of modulation mode，elicit BPSK and PPM in the resolvable multipath and indiscernibility multipath error rate expression are induced. For the same fork index and signal-to-noise ratio，two kinds of multipath component signals under different modulation mode of simulation analysis are conducted. The simulation results show that，under the same modulation mode，distinguish the multipath error rate resistance is superior to the indiscernibility multipath situation. No matter in distinguish multipath or indiscernibility multipath, BPSK modulation is superior to PPM modulation method on resistance error rate.