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In pipeline defect detection using ultrasonic guided wave,the defect echoes are not easily to be recognized because of its low signal-to-noise ratio (SNR),which becomes the main obstacles of ultrasonic guided waves detection.A novel method of defect detection based on chaotic oscillator has been proposed.The weak periodic signal in noise can be detected via the trasition of phase trajectory of chaotic system from chaotic motion to periodic motion.The parameters of chaotic system was determined according to the ultrasonic guided wave detection.The chaotic oscillator was proved to have good immunity to noise by using chaotic system to processdifferent amplitudes of Gaussian white noise.The case of single defect and double defects were simulated via finite element software ANSYS.The numerical result show that the proposed method can be used to expand the detection range and improve the sensitivity in pipes defect detection.