As the ISDS mechanism has been widely applied, its shortcomings have been gradually magnified, and the host country's right to regulate has been constantly challenged by foreign investors in international investment dispute settlement, and the sovereignty and public interests of the host country have been undermined as a result. This paper examines the existing problems of the host country's right to regulate, and analyses in depth the motivation for strengthening the host country's right to regulate in the context of the reform of the ISDS mechanism, taking into account past cases and practical experience. At the same time, by comparing and analysing the relevant theories of domestic and foreign scholars on the ISDS mechanism, the paper highlights the necessity of strengthening the host country's right to regulate in order to maintain a balance between the interests of both the host country and the investors, and proposes a feasible and practicable reform plan in this regard.