The invention discloses a subcarrier perceiving method in a wireless communication network. The method comprises the steps of firstly defining the initializing of a multi-level wiener filtering process, then executing iteration processes for multiple times to obtain a covariance matrix of an expected signal, then calculating a Gerschgorin disk radius and a Gerschgorin disk estimator based on the covariance matrix to estimate the number of occupied subcarriers, and finally judging the positions of the occupied subcarriers according to the magnitude of each subcarrier power and determining idle subcarriers and occupied subcarriers. The method provided by the invention has the characteristics of utilizing the orthogonality of signal subspaces and noise subspaces to judge without the dependency on the traditional subjective judgment threshold, having robustness on noise uncertainty without the need of apriori information of noise power, and belonging to a blind perceiving method without the need of statistic characteristics of channel information and signals. The method can be used for effectively restraining the influence of the background noise in the wireless communication network to system performance and is low in calculating complexity and strong in feasibility.