This paper describes the intermittent chaos detection principle,combined with differential form the double Duffing oscillator difference system to the weak signal frequency detection,gives the detailed steps of the method and flow chart.Use the feature that Duffing oscillators with specific reference frequency are insensible to other frequency signal’s interference,only sensitive to a small part of the nearby specific frequency signal,it comes to a conclusion that small amplitude periodic motion and intermittent chaos motion may appear at the same time in the detection system,which can be used to detect complex frequency signals.At last,takes the single frequency signal and the complex frequency signal detection for simulation,the results show that,compared with traditional Duffing oscillator array method,this method not only reduces the array number,and improved frequency detection bandwidth without affecting the detection accuracy,reduces the calculation amount,so it’s much better than the traditional method for frequency detection.