Natural gas hydrate (NGH) holds great promise as a source of clean energy. It is critical for acquiring the largest possible in situ NGH core for NGH eigen features and resource assessment. However, the existing NGH coring technology has limitations, such as temperature increments, limited coring diameters, low coring rates, and complex coring structures. Therefore, this study designs and proposes an NGH freezing coring (NGHFC) method and verifies the freezing and coring capacities of the NGHFC method in laboratories and experimental wells. Results suggest that NGHFC shows good freezing and heat-retention properties. A freezing core heat transfer model is developed. According to the actual air temperature and operating time, the optimum initial temperature of the cold source can be determined using this model. The average coring rate of NGHFC can reach 77.86%. The research results will provide a new idea of coring gas hydrates.