Abstract: The release rate of copper ion is the main indicator for evaluating the antifouling performance of copper-containing antifouling paints, and the accuracy and efficiency of its test methods are of great significance for the screening and evaluation of antifouling paint formulations. Through the self-made indoor antifouling paint leakage test device, the variation law of copper ion release rate of antifouling paint in real seawater environment and indoor simulated environment is compared, and the relevance and difference between the two test methods are compared. The results show that the variation trend and final results of the copper ion release rate curves tested by the two test methods are consistent, and that the indoor simulated environmental method is faster, more accurate and more convenient.