It is a hotspot of communication field to research Cognitive Radio, which is also the direction of communication technology developing. The technology of spectrum sense and detection is of most important part and takes a critical role in CR theory. In this paper, it is introduced that Secondary User senses and detects the appearance of the licensed Primary User based on Radio Frequency Fingerprint (RFF) recognizing technology. RFF Technology application scheme in CR is suggested, realizing in transceiver of Secondary User (SU). Two steps are introduced for improving capability of detection: First, based on distribution network, cooperative RFF detection is realized among the SU; second, sensing frequency band is shortened and Base Station only deals with Primary User (PU) in the range of local cell. The critical technologies are analyzed and simulated, including transient extractor, feature extractor and recognizing arithmetic. The results of simulation show that detection to Primary User based on Radio Frequency Fingerprint can efficiently recognize PU with correct and quick detection capability.