We propose a modulation scheme of ultra-wideband (UWB) pulse amplitude bas ed on a lithium niobate Mach-Zehnder modulator (LiNbO₃MZM).In the scheme,th e clock signal is added to the electric signal.and pulse amplitude modulation (P AM) can be realized by this method.The scheme is simple and integrated easily.By using the software of OptiSystem 7.0,the generated ultra-wideband (UWB) monocy cles with different power levels of laser device (LD),different optical carrier wavelengths,different input signal pulse widths,different modulation rates,diffe rent time delays and different transmission distances are experimentally studied and analyzed.The results show that this scheme has good tolerance to the input signal pulse width,and it is insensitive to the wavelength change.This shceme al so has good performance in transmission,and the modulated signal can transmit fo r 10km.In order to get distortionless modulated signal,the power of LD and modu lation rate must be within a certain range.According to the analysis,the maximum of laser power is 6dBm and the modulation rate is 30Gbit/s.The time delay sj hould be controlled in a permissible range of inaccuracy.Overall,this scheme has considerable advantages,and the output signal can satisfy the existing communic ation system needs.