The research for Dynamic Spectrum Access (DSA) and cognitive radio network (CRN) becomes one of the focuses in wireless network currently. However, as many other new techniques, in the initialization period, the security factors in CRN are out of focus. This paper describes the special characteristics of cognitive radio (CR) and CRN, and analysis the current and potential security threats that due to their characteristics. Besides some countermeasures and keys need to attention are mentioned. The goal of this paper is to assist CR designers and the CR application engineers to consider the security factors in the initial development period of CR techniques.