A cognitive UWB system and a cognitive UWB data communication method. The system includes a cognitive UWB transmitter and a cognitive UWB receiver. The cognitive UWB transmitter includes a channel encoder for correcting error of data, a preamble inserter for inserting a preamble into the data, a mask information inserter for inserting mask information into the data, a cognitive UWB pulse generator for generating a pulse based on the mask information and the channel environment information, a pulse position modulator for modulating the pulse, and a radio frequency transmitter for wirelessly transmitting the data. The cognitive UWB receiver includes a radio frequency receiver for wirelessly receiving data, a synchronizer for synchronizing time of data, a spectrum detector for detecting the channel environment information, a mask information extractor for extracting the mask information, a cognitive UWB pulse generator for generating a pulse, a pulse position modulator for demodulating the pulse, and a channel decoder for correcting error of the demodulated data.