Termodynamic data on methane hydrate formation in the presence of ammonia are very important for upgrading of ammonia synthesis vent gas using hydrate formation. This paper is focused on the formation conditions of methane hydrate in the presence of ammonia and the effects of gas-liquid ratio and temperature on the separation of vent gas by hydrate formation. Equilibrium data for methane hydrate within an ammonia mole concentration range from 1% to 5 % were obtained. The experimental results indicated that ammonia has an inhibitive effect on hydrate formation. The higher the ammonia concentration, the higher is the pressure reguired for methane hydrate formation would be. The primary experimental results showed that when volume ratio of gas to liquid was 80:1 and temperature was 283.15 K, total mole fraction of (H2+N2) in gas phase could reach 96.9 %.