A two-level latch mechanism for an operation mechanism of a circuit breaker is provided. The operation mechanism includes: a tripping component, a left side plate, a right side plate, a latch, a half shaft, a lever, and a main shaft. The tripping component, the latch and the lever are mounted between the left side plate and the right side plate. The half shaft and the main shaft penetrate through the left side plate and the right side plate, and extend out of the left side plate and the right side plate. The tripping component, the latch, the half shaft, the lever, and the main shaft move in linkage. The tripping component includes a tripping buckle and a latch surface is disposed on a second end of the tripping buckle. The tripping component, the latch component and the half shaft component form a two-level latch.