Hydrogen is considered as one of the most superior future energy carriers due to its clean, low-carbon and extensive sources. However, a wide flammable concentration range and low ignition energy of hydrogen can cause potential safety hazards, including hydrogen jet flames. Currently, a series of hydrogen jet flame experiments were performed in an enclosed compartment with internal dimensions of 1.82 m (L) × 1.99 m (W) × 1.85 m (H), using different nozzle diameters and stagnation pressures. The results indicate that the combustion process can be divided into four stages, including growth stage, relatively stable stage, stretching stage, and self-extinguishing stage. The oxygen concentration in an enclosed compartment decreases rapidly with increasing stagnation pressure. The self-extinguishing time is positively correlated with the compartment volume and negatively correlated with the mass flow rate. Based on thermal equilibrium analysis, the correlations for average gas temperature rise and oxygen concentration were proposed