Abstract: The vortex wave flow field of symmetric channel has a wide range of applications in industrial mass transfer and heat transfer. To further analyze the flow characteristics and variation laws of the vortex wave flow field within symmetric channel under laminar flow conditions, 2D PIV measurements was carried out to obtain data of instantaneous flow velocity vector field, then modes were decomposed and vortex wave flow field reconstructed using proper orthogonal decomposition(POD) technology. According to the reconstruction of the flow field, analysis were carried out for mean velocity profile, pulsation intensity of flow field, velocity and spectral distribution of the characteristics points, etc. of the vortex wave flow field within the symmetrical channel. The results show that the first 15 POD modes could characterize the dominant vortex wave flow field structure, the first and the third modes were a pair of vortices with opposite rotating, while the second mode had a vortex and the wavy mainstream feature. Five vortex core positions were extracted as the flow field feature points. Analysis based on POD reconstructed stream field. Analysis shows that the average speed distribution in the flow direction is parabolic, and the normal average speed distribution is symmetrical; flow pulsation intensity is greatly influenced by the wall, the normal fluctuation intensity distribution exhibits a parabolic shape; the speed pulsation features of feature points 1^#, 4^#, 5^#(closer to the center mainstream) are influenced by mainstream pulsation strength, the velocity distribution of feature points is affected by pulsation speed frequency of 0.15 Hz frequency and the natural frequency of the flow field 0.35 Hz together; the flow velocity of feature points 2^#, 3^# has a fading trend, the normal speed variation amplitude is large in the early stage.