An arc extinguishing mechanism of a power circuit breaker based on gears, comprising a drive mechanism (77), a trigger mechanism (78), and a heat absorbing mechanism (80); when the circuit breaker is in use, an arc trigger wrench (5) is pulled to swing towards one side of an arc trigger block (6), the arc trigger wrench (5) driving the rotation of a drive shaft (16), and the drive shaft (16) rotating such that an arc is produced between the arc trigger wrench (5) and the arc trigger block (6), and heat transferred from the arc onto a heat conducting plate (57) is dissipated by the airflow from the movement of the heat conducting plate (57); when the arc trigger wrench (5) and the arc trigger block (6) need to be separated, the arc trigger wrench (5) is pulled to swing away from one side of the arc trigger block (6), the arc trigger wrench (5) driving the rotation of a drive shaft (16), and the drive shaft (16) rotating such that an arc is produced between the arc trigger wrench (5) and the arc trigger block (6), and heat transferred from the arc onto a heat conducting plate (57) is dissipated by the airflow from the movement of the heat conducting plate (57); thus, the high temperature arc produced between the arc trigger wrench (5) and the arc trigger block (6) when the circuit is open or closed can be rapidly dissipated.