Abstract: A spectrum sensing method based on the high order cyclic statistic(HOCS) in cognitive radio was presented according to the strict cyclostationarity of the HOCS. The binary hypothesis test model and the test statistic are constructed and the explicit formula of the detection probability is derived by exploiting the asymptotic optimal estimation theory. The computational complexity of the proposed method has nearly the same order as that of energy detection(ED) by comparing their real multiplication operation times. The simulation results show that the new scheme has superior performances of detection and resistance to same frequency interference compared with the conventional spectrum sensing methods.