The results of mathematical and experimental modeling of dissociation of pore methane hydrate in ice- and gas-bearing sediments with a decrease in the external pressure below equilibrium are presented. The described model of pore gas hydrate dissociation at negative temperatures, along with the experiment, makes it possible to calculate the kinetics of this process. A comparative analysis of the results is conducted. The proposed mathematical model confirms the trend of decreasing hydrate saturation of frozen soil in the form of obtained previously in experiments. These experiments have made it possible to calculate the coefficients A and n, while the mathematical modeling shows how these coefficients depend on the problem parameters. The theoretically estimated properties of the coefficient fully confirm the experimental data. The results of experimental and mathematical modeling have implications for key factors that determine the self-preservation of pore methane hydrates in frozen sediments.