Many substation equipments were damaged during Wenchuan earthquake. The seismic behavior of circuit breaker, main component of substation, should be studied. In this paper, shake table tests on a real full size circuit breaker are carried out to study the seismic behavior of the equipment. Seismic responses of accelerations, displacements and the strains of the key parts of the equipment are measured under different ground motions with different levels of peak ground accelerations. These parameters are used to analyze the dynamic characteristics, seismic performance of the equipment as well as the load-carrying capacity of the equipment bracket. The test results show that the bottom of the post insulator is seismic vulnerable part of the equipment due to its complex stress state. Dynamic amplification effects of the equipment bracket should be considered in seismic design of the equipment.