The effectiveness of cathodic protection on rotating equipment, such as drum filters is influenced by rotation parameters. Herein, a test set, on which test-pieces made of Q345B steel can be inserted, was designed to simulate the rotation circumstance of drum filters in an artificial seawater. Then, the effectiveness of cathodic protection on the test-pieces of Q345B steel was assessed according to the known orthogonal experiment procedure in terms of the varying parameters such as protection potential, duty cycle, and rotation frequency etc. The results show that as the rotation frequency increases from 0.010 r/d to 0.020 r/d, the degree of cathodic protection effectiveness first increases and then decreases, with the best protection effectiveness emerges at the frequency of 0.015 r/d, where the protection degree reaches up to 90.67%. This may be related to the flow rate and the morphology of corrosion products. As the duty cycle increases from 0.25 to 0.75, the degree of cathodic protection gradually increases. Regarding the protection potential, when the set protection potential negatively increases from -0.80 V to -1.25 V (vs. SSC), the degree of cathodic protection increases from 12.43% to 90.67%. This may be related to the proportion of cathodic polarization products CaCO₃ and Mg(OH)₂. When the proportion of CaCO₃ is low and that of Mg(OH)₂ is high, the Ca-containing deposition layer becomes tighter, resulting in better cathodic protection effectiveness.