Abstract: Objective: To better control the stability, safety, comfort, environmental vibration and noise of train operation, it is necessary to conduct analysis and research on track irregularity spectrum specifically for Chengdu Metro lines. Method: Dynamic tests are performed using a track inspection vehicle to detect the superposed state of elastic deformation and permanent deformation of Chengdu Metro Line 7 tracks. The test items mainly include vertical irregularity, lateral irregularity, horizontal irregularity, and gauge irregularity of both left and right rails. The widely used power spectral density estimation method-Welch method (improved periodogram method) is employed to calculate the power spectral densities of long-wave vertical irregularity, lateral irregularity, gauge irregularity, and horizontal irregularity of the tested tracks within the statistical period. The frequency characteristics of the track irregularity spectrum of Chengdu Metro Line 7 are summarized and compared with the typical track spectrums in China and abroad. Based on the nonlinear least squares method, the curve fitting of the track spectrum of Chengdu Metro Line 7 is carried out using the three main line spectrum formulas of China.Result & Conclusion: The track joint gaps affect the long-wave irregularity of the track; the track irregularity spectrum of Chengdu Metro Line 7 exhibits narrowed peaks at spatial frequencies that are integer multiples of 0.04 m-1; this spatial frequency corresponds to the length between two adjacent welds on continuous welded rails, indicating that the weld irregularities become a significant issue affecting the track condition and train operation; the track smoothness of Chengdu Metro Line 7 is better than that of the common speed railways in the United States, Germany and China (especially in the long-wave frequency range with wavelengths greater than 19 m), but not as good as that of the high-speed railway ballastless track in China; the three main line spectrum formulas of China are more suitable for Chengdu Metro Line 7.