In the paper, the necessity to establish the operation testing system for subsea utility tunnels is analyzed; it is proposed that the structural safety, hydrogeological environment features, operation conditions and service conditions of the subsea tunnel, as well as the requirements of the utility lines, should be taken into account when the operation testing system is established; it is believed that the testing can be classified into routine testing, regular testing, special testing and dedicated testing; and the testing frequency, testing items, testing methods, technical condition assessment criteria and the weight values of different indices are proposed. The mentioned testing system has been used for Qianwan tunnel in Shenzhen, and some of the testing results are provided. Conclusion is drawn that the testing items and assessment criteria provided in the paper can reflect the safety and service conditions of the subsea utility tunnel; the mentioned indices, which be achieved by using the testing methods proposed in the paper, can provide scientific decisionmaking basis and technical support for the disease treatment of subsea tunnels.