In order to reduce NOx and the ignition loss generated by the pulverized coal combustion, the secondary gas fuel injection method is investigated at the pulveried coal combustion test facility (standard load: 6.54×105kcal/h). The secondary gas fuel injection method is to inject the gas fuel (H2, CH4, C3H8) in the flame for the NOx reduction.In the case of using CH4 or C3H8 as a secondary fuel, the NOx concentration is reduced for both combustion conditions of non-two stage combustion and stage combustion. But, H2 doesn't have any effect for NOx reduction.For CH4 or C3H8 injection, the NOx reduction effect is different for the location of the injection point. At the case of non-two stage combustion condition, the better injection location for Nox reduction is distant from the burner and C3H8 is more effective at many points for injection than CH4. On the contrary, at the case of two stage combustion the location near the burner is suitable for NOx reduction in both CH4 and C3H8 injection.