Abstract: Performance of spectrum sensing not only relies on sensing methods in the Physical（PHY)layer，but also depends on cooperative scheduling in the medium access control（MAC)layer.A dynamic and variable timedivision multipleaccess（DVTDMA)scheduling mechanism is proposed to combine with a dualstage collaborative spectrum sensing（DCSS)model in poor electromagnetic environments of cognitive radio networks.Moreover， closedform expressions of average sensing time are derived， and throughput optimization problem is presented and analyzed by simulation， as well as the advantages of collaboration are discussed.The simulation results indicate that the proposed DCSS scheme with the DVTDMA mechanism，when compared to the single collaborative spectrum sensing scheme， is more beneficial to improve sensing accuracy and sensing speed，as well as throughput of cognitive networks.