The invention relates to a test device in the field of automobiles and aims at providing a novel device and a novel method for testing an ESP/ABS (Electronic Stability Program/Anti-lock Brake System) energy accumulator. The device comprises an ESP/ABS to-be-tested piece positioned in a test loop, wherein the test loop comprises a hydraulic steel cylinder connected with a reciprocating apparatus, a proportional valve, a pressure sensor, a displacement sensor and an industrial personal computer. According to the device and the method, an assembly is not required to serve as a test piece, equipment required for test is simplified or omitted by virtue of a pneumatic control liquid, and the increase/decrease of the hydraulic pressure of an automobile brake loop can be simulated, so that the test environment and actual use operating condition of the ESP/ABS to-be-tested piece are more approximate. According to the device and the method, by virtue of performing the PV performance curve and endurance test of the energy accumulator, the performance of the ESP/ABS energy accumulator is directly, accurately and rapidly tested, and the failure risk can be predicated in advance and reduced.