The invention discloses an optimized Internet of Things multi-band cooperative spectrum sensing method. The method comprises: dividing a whole available frequency band into non-overlapping frequency bands; carrying out noise uncertainty-based dual-threshold energy detection on each sub-frequency band; introducing multi-band cooperative awareness, and the cognitive user only performing joint judgment on the hard judgment result, the joint judgment adopting a 'majority' judgment criterion, fusing the statistics of the sub-bands under the condition that no main user signal exists in the joint judgment result, and using a soft judgment optimal threshold based on a minimum total error probability criterion to obtain a final judgment result. Simulation results show that the method has high detection probability.