The gas hydrate reserve is abundant in the Shenhu Sea area， which provides a large amount of energy reserve for our country， and the problem of the shortage of energy can be solved effectively by means of efficient exploitation. Inhibitor injection method is one of the main methods to extract gas hydrate. Methanol is an excellent inhibitor with good inhibition and low viscosity. In this paper， a three-dimension， three-phase and four-component numerical model for gas hydrate exploitation in the sea area was established according to the actual geological parameters. The dynamic characteristics of hydrate exploitation in hydrothermal methanol solution were studied by means of numerical simulation using the horizontal well layout method with production wells on both sides and the injection well in the middle. The extraction effects of single depressurization method and hot water injection method were compared with that of the methanol inhibitor injection and the results show that the later can increase the reservoir temperature and promote the decomposition of hydrate， which improves the shortcomings of the former two methods. It has higher initial gas production rate， higher initial gas-water ratio and higher hydrate decomposition effect， which is a competitive exploitation method.