Abstract: In view of the practical problem that the impressed current method fails to effectively protect the buried long-distance pipeline section crossingwater area, the joint cathodic protection method ofimpressed current and sacrificial anodewas used for the maintenance and treatment. Herein, the interaction law of impressed current with the magnesium alloy sacrificial anode for cathodic protection, as well as the influence of coating damage rate on the effect of joint cathodic protection, was studied through electrochemical experiments. Meanwhile, the protection effect of sacrificial anode was evaluated with finite element simulation and calculation. Besides, the laboratory research results were also verified in the field. The results show that there is anode output current at the sacrificial anode when the impressed potential is positive to the open-circuit potential of the sacrificial anode, and there is cathode input current at the sacrificial anode when the impressed potential is negative to the opencircuit potential of the sacrificial anode. With the increase of the impressed potential and the coating damage rate, the output current of the sacrificial anode decreases, the working potential shifts negatively, and the effect of cathodic protection is weakened. The cathodic protection potential of the under-protectedsection of the target pipeline near the water area could meet the -0.85 VCSE criterion under the joint cathodic protection of impressed current and sacrificial anode. Compared with the impressed current cathodic protection method, the joint cathodic protection effect is significantly improved, with the protection rate increased from 52.6% to 100%, and the pipeline potential is distributed more uniformly. Therefore, the sacrificial anode could be used as an auxiliary cathodic protection measure for the special environmental pipelines with local under-protected sections or positive potential.