The cathodic polarization behavior of X60 steel bar without and with concrete counterweight layer in static and flowing artificial seawater of different salinities (5‰, 16.8‰, 26.7‰) and real mud, the later was tokened from the Hangzhou bay coastal wetlands, was assessed via steady-state constant potential polarization, electrochemical impedance spectroscopy (EIS), and numerical simulation methods, aiming to understand the effect of concrete counterweight layer on the cathodic protection of submarine pipes in nearshore marine environments. Meanwhile, the resistivity of the concrete weighted layer was also measured, and the cathodic protection potential distribution and sacrificial anode output current of the pipe in the presence of the concrete weighted layer were obtained. The results showed that when the polarization potential was reached -0.85 V (CSE) in static seawater of salinities of 5‰, 16.8‰, and 26.7‰, as well as sea mud, the cathodic polarization current density required for the bare X60 steel was about 3.5-8 times that required for X60 steel with a concrete counterweight layer. In 2 m/s flowing seawater, the difference in cathodic polarization current density required for X60 steel with concrete counterweight layer by the corresponding potential is relatively small compared to that in static seawater. The flow velocity will significantly increase the cathodic polarization current density required for bare X60 steel, which is related to the increased oxygen diffusion and the destruction of calcium deposition layer due to the increased flow velocity. While the concrete counterweight layer hinders this effect of flow velocity. The change in polarization resistance measured by electrochemical impedance spectroscopy is consistent with the change in polarization current density. At the same time, the resistivity of the concrete counterweight layer in seawater is about 70 times that of the corresponding seawater resistivity, and the resistivity of the concrete counterweight layer in marine mud is about 37 times that of the corresponding marine mud resistivity. The numerical simulation results show that the concrete counterweight layer reduces the cathodic polarization current density, resulting in a significant negative shift and small potential attenuation of the cathodic protection potential. The concrete counterweight layer reduces the output current of the sacrificial anode, resulting in a slightly positive shift of the cathodic protection potential. In a word, the concrete weighted layer has a significant effect on the improvement of the cathodic protection effectiveness of submarine pipes.