Security issues of spectrum sensing have drawn a lot of attentions in Cognitive radio networks(CRNs).Malicious users can mislead the network to make wrong decision about the states of channels by tampering spectrum sensing data.To defense against Spectrum sensing data falsification(SSDF) attack,we propose a neighbor detection-based spectrum sensing algorithm in distributed CRNs,which can detect attackers with the help of neighbors during spectrum sensing to improve the accuracy of decision making.The proposed scheme can also guarantee the connectivity of the network.Simulation results illustrate that the proposed scheme can defense against SSDF attacks effectively and reach the unified information of spectrum sensing data. Security issues of spectrum sensing have drawn a lot of attentions in Cognitive radio networks (CRNs). Malicious users can mislead the network to make wrong decisions about the states of channels by tampering spectrum sensing data. To defense against Spectrum sensing data falsification (SSDF) attack, we propose a neighbor detection-based spectrum sensing algorithm in distributed CRNs, which can detect attackers with the help of neighbors during spectrum sensing to improve the accuracy of decision making. The proposed scheme can also guarantee the connectivity of the network. Simulation results illustrate that the proposed scheme can defense against SSDF attacks effectively and reach the unified information of spectrum sensing data.