In this communication, we report dissociation conditions of methane hydrates in the presence of (0.1 and 0.4) mass fractions of polyethylene glycol-400 aqueous solutions in the temperature ranges of (276.8 to 287.3) K and (276.1 to 285.6) K, respectively. The equilibrium data were measured using an isochoric pressure-search method, It is shown that low concentration of polyethylene glycol 400 in aqueous solution has almost no inhibition effect on the dissociation conditions of methane hydrates, while this effect is not ignorable at high concentrations.