A UWB multi-functional modulator scheme based on cascade of phase modulation (PM) and filters was presented. This scheme was simple and could switch a variety of UWB modulation format flexibility by simple pre-coding to realize on-off keying(OOK), pulse bi-polar modulation(PBM), and pulse shape modulation(PSM). The generated three kinds of signal contained only a single wavelength, which can be transmitted over optical fiber without complex nonlinear control and dispersion management. By simulating through the software of Optisystem, the impact of light source power, modulation rate, and the system error of two PM modulators and filters on modulated signal was investigated. In addition, the transmission characteristics of modulated signals in single were also discussed. We found that the input power and modulation rate should between a certain range in order to get optimum UWB modulation signals.<<参考文献原文>Ge Lijia, Zeng Fanxin, Liu Yulin, et al. Ultra Wideband Impulse Radio[M]. Beijing: National Defence Industry Press, 2006: 5-6. (in Chinese)葛利嘉, 曾凡鑫, 刘郁林, 等. 超宽带无线通信[M]. 北京: 国防工业出版社, 2006: 5-6.