In order to understand the suppression effect of the V-groove structure on vortex-induced vibration (VIV), a comparative study of the wakes behind circular cylinders with the V-groove surface and smooth cylinder surface is performed. A recirculation water tank is established for the experiment, and particle image velocimetry (PIV) is employed to measure research the wake characteristics of smooth cylinders and circular cylinders with the V-groove surface. The result show that in comparison to the smooth cylinder, the length of the recirculation region behind the V-groove cylinder is extended. The POD mode energy of the circular cylinders with the V-groove surface is smaller than that of the smooth cylinder, this indicates that the V-groove structure suppresses the vortex shedding process and delays the formation of vortex streets. At the same time, the V-groove structure has a certain influence on POD mode coefficients and the coherent structure of POD modes. It is concluded that it is feasible to use the POD method to study the flow characteristics of the V-groove cylinder.