The invention discloses a spectrum sensing 
algorithm based on 
variational mode decomposition, and solves the problem that a 
signal at a receiving end is interfered by a 
noise background in the prior art. The method comprises the following steps of: 1, generating a 
simulation signal BPSK; 2, taking the mean value of the instantaneous frequencies of the components as a 
decomposition parameter, determining an optimal mode 
decomposition number K according to a change curve of the 
decomposition parameter, and setting an appropriate 
penalty factor alpha; 3, performing variational mode decompositionon the BPSK 
signal according to the obtained decomposition parameters; 4, respectively carrying out power spectrum 
estimation on the obtained L intrinsic 
modes; 5, taking the ratio of the sum of the 
spectral line intensities of the intrinsic 
modes to the sum of intensities of all the intrinsic 
modes as a test statistic; and 6, comparing the obtained test statistics with a judgment threshold, and making a final judgment. According to the method, the equivalent band-pass filtering characteristic and the Wiener filtering structure of 
variational mode decomposition are utilized, frequency bands are better divided, and denoising 
processing is better carried out; and compared with a traditional power spectrum segmented cancellation 
algorithm, the 
detection performance can be remarkably improved.