As one of the key technologies of cognitive radio, spectrum sensing is extensively and deeply studied. In the case of low SNR environment, the threshold of traditional double threshold method is fixed, which leads to poor perception effect. To solve the problem, an adaptive double-threshold cooperative spectrum sensing algorithm is proposed. The weight is obtained by calculating the SNR of each node. The weights are obtained. The decision threshold is adjusted, and the current judgment result is fully correlated with the time before and after, and the final decision result is obtained by fusing the decision information of each node. The results of theoretical analysis and Monte-Carlo simulation show that the algorithm can effectively improve the spectrum sensing performance compared with the traditional double threshold detection algorithm and the weighted double threshold detection algorithm.