A novel approach to generating ultrawideband(UWB) chaotic pulse is proposed and demonstrated by using optical feedback laser diode. The chaotic laser is generated through a commercial C-band laser diode (LD) with external feedback. This continous-wave chaotic laser is modulated by utilizing an electro-absorption modulator. And then, a series of chaotic pulses are generated, their radio frequency (RF) spectrum can be controlled by adjusting the bias current and feedback strength of the LD. The UWB chaotic pulses with center frequency of 4.0 GHz and fractional bandwidth of about 181% and 214% are obtained. The experimental results agree well with the numerical demonstration. The proposed method is simple, and the spectrum property can be controlled easily. It is suitable for UWB-over-fiber communication systems as photonic microwave signal source.