A multi-user communication system based on photonic generation of coded ultrawideband (UWB) signal is proposed and demonstrated. The optical fiber is used for the transmission of the coded UWB signal generated by an optical method at the transmitter. The receiver calculates the cross correlation of the coded UWB signals and the signature codes to get the user information and data information. The proposed system has advantages such as simple expansion, easy receiving, long distance transmission, and tunability. The core component in the system is the optical frequency discriminator combined by multi-channel fiber Bragg grating (FBG) filter and dispersion fiber. Different chip-combinations in the signals represent different users. It needs only to tune the wavelength of the lasers for user-switching in this system. The coded UWB signals for different users are experimentally generated, and the user information and data information are recovered correctly. The proposed system realizes the whole communication process.