Abstract: L（0,2） longitudinal mode guided wave was used to detect the non-permeable crack defects in gas pipeline with different circumferential angles. Guided wave detection method based on time reversal was adopted to focus the guided wave signal energy at the defect and improve the amplitude of the defect echo signal, and the variation law of signal reflection coefficient with the circumferential angle expansion before and after time-reversal method was studied, and the circumferential distribution of guided wave displacement was drawn to locate the crack defect in axial and circumferential direction, and the relationship between the energy distribution of time reversal guided wave and the circumferential size of the crack was explored. The numerical simulation results show that the time-reversal method is more effective in amplifying the defect signal of small cracks. With the increase of the circumferential angle of the crack, the signal amplification coefficient decreases gradually and tends to 1, and the time-reversal guided wave energy gradually spreads along the circumferential direction at defect position. The crack can be effectively identified and located in the circumferential and axial direction by the time-reversal method.