The invention relates to a device for detecting the strength characteristic of a dynamic dielectric of a contact gap of a breaker and belongs to the technical field of electricity generation switch devices, power transformation switch devices and distribution switch devices. The device for detecting the strength characteristic of the dynamic dielectric of the contact gap of the breaker comprises a high-voltage direct-current power source, a charging resistor, a capacitor, a voltage measuring device and a travel measuring device, wherein the capacitor is connected with the contact gap of the breaker in parallel and then is connected with the charging resistor and the high-voltage direct-current power source in series, and the voltage measuring device and the travel measuring device are connected with the breaker. According to the device for detecting the strength characteristic of the dynamic dielectric of the contact gap of the breaker, through one-off closing and opening operation of the breaker, the strength characteristic, existing during closing, of the dynamic dielectric of the contact gap and the strength characteristic, existing during opening, of the dynamic dielectric of the contact gap can be obtained, operation is easy, and control is convenient.