Abstract: By applying the boundary element numerical simulation commercial code BEASYCP, the cathodic protections of truck line and storage tank are numerically simulated. The effect of bridge connecting equalizer on the parallel pipeline is studied. The potential distribution of the outer storage tank floor with deep well anode and meshed anode is simulated. The On/Off IR drop and the grounding current for storage tank floor with meshed anode are analyzed. The investigation shows that the distance between previously constructed stations, end protection potential and the coating resistivity of later built pipelines are the main factors for the cathodic protection potential and the current distribution of later built pipelines; the cathodic protection of the tank floor can not totally be covered since the potential distribution is uneven; the distribution of the polarization potential and current on the tank floor depend on the polarizing performance of the tank floor material on the tank base, ground electrode in the soil, and the relative value of the current density between them during polarizing.