The present invention discloses a method of multiple systems sensing for coexisting radio networks, including: performing energy detection and carrier locking; detecting the fundamental frequencies; and identifying the corresponding active systems from the detected fundamental frequencies and the evaluation of the estimated power spectrum density vector or the estimated trispectrum matrix. Based on the method, an apparatus capable of multiple systems sensing is presented. Furthermore, the present invention also provides an apparatus of multiple systems sensing for coexisting radio networks.