To enhance the energy efficiency of biogas and reduce environmental pollution, impurities such as CO2 and N-2 must be removed. In this context, hydrate-based gas separation (HBGS) is a novel technology that has been utilized in gas purification. As such, the hydrate phase equilibrium data of the CH4/CO2/N-2 gas mixture are crucial for application of the HBGS process in biogas separation. This study presents our investigation into the phase equilibrium conditions for the hydrates of synthesized ternary CH4/CO2/N-2 biogas mixtures. All experiments were conducted at 276.2-286.3 K and 2.59-8.84 MPa using an isochoric method with different ternary CH4/CO2/N-2 gas concentrations. The results obtained herein indicated that the hydrate phase equilibrium conditions shifted to lower pressures and higher temperatures with increasing CO2 contents. In addition, with a N-2 content of about 10%, the hydrate phase equilibrium data of the ternary gas mixtures approached that of pure CH4.