The invention discloses a low-nitrogen gas boiler burner. The low-nitrogen gas boiler burner comprises a mixing pipeline, an igniter, a metal fiber burning head, a gas flow control loop, an air flow control loop and a ratio meter. The ratio meter is arranged between the gas flow control loop and the air flow control loop, the ratio of natural gas to air can be controlled by adjusting the gas flow control loop and the air flow control loop, thus, the flow rate and ratio of mixed gas are more stable, and the efficiency of the burner and the burning safety of a boiler are improved. A two-stage air supply mode is adopted, and the pressure loss of primary air and fuel gas in a twisted blade mixer is supplemented, the mixedness of the natural gas and the air is improved, the temperature of the metal fiber burning head is lowered, the retention time of smoke in a high-temperature zone is shortened, and generation of NOx is effectively inhibited. Circulation flow occurs inside a flame through air supplied by secondary rotational flow, the uniformity of the flame temperature is improved, and the efficiency of the burner is improved. The low-nitrogen gas boiler burner has high innovativeness and wide practicality.