The utility model discloses a novel 126 kV self-energy type SF6 high-voltage circuit breaker, which comprises a base, a bracket arranged at the lower ends of the two sides of the base, a terminal post arranged above the base, a spring operation mechanism arranged below the base, a three-pole connecting windpipe and a density meter. The three-pole connecting windpipe and the density meter are arranged in the base. The 126 kV self-energy type SF6 high-voltage circuit breaker is characterized in that the terminal post comprises an arc-extinguishing unit, a connecting lever box and a lower pillar unit connected with both the arc-extinguishing unit and the connecting lever box. The arc-extinguishing unit comprises an upper wire outgoing base, a static arc contact, an arc-extinguishing chamber ceramic sleeve, a pull rod shaft, a lower wire outgoing base, a large nozzle, a small nozzle, a movable contact and an air cylinder. According to the technical scheme of the utility model, the diameter of the static arc contact is increased, so that the arc ablation resistance of the circuit breaker is effectively improved. The electrical service life of the circuit breaker is prolonged. Meanwhile, the clearance between the static arc contact and the movable contact is enlarged, so that the insulation redundancy of the circuit breaker after the switch-off operation is increased. The insulating property of the circuit breaker is improved. The circuit breaker is low in rated pressure, so that the usage amount of SF6 gas is lowered. The novel 126 kV self-energy type SF6 high-voltage circuit breaker is in accordance with the development trend of energy conservation and environmental protection.