According to the rclationship between the operating mechanism anrl the arc exlinguisl.1 chamber of a puflcr circuit hrcakct, mathetnatical models lirive been developed, and the influences of tlie hydraulic mcchanisiii and the chamber on the moving clixicteristics of the puli'cr circuit breaker 1iive been studied. Tlicrchrc, adjiistiiig the diameter of tlic drain oil aperturc of thc opcrating mechanism is an cffcclivc way to ohtaiii wirious breaking cliarxteristics. Hcncc, it is possible to rezlise 'intelligciit operation'. The sirnuletion results wi-e showti lo be in eordmcc with thc experiment results; atid it is also shown ha1 tlic models are more universal and practical.