The invention discloses a device for detecting a storage battery, comprising a CPU, an operational amplifier, a multi-way switch, a digital/analog (D/A) converter, a high-power MOS tube, a coupling capacitor, a programmable bandpass filter and an analog/digital (A/D) converter. The high-power MOS tube is connected on a storage battery discharge detection circuit in series. The CPU is used for controlling discharge of the storage battery so as to generate excitation current. The detected current signals and voltage signals are amplified by the operational amplifier after the coupling capacitor subtracts the direct current component, and the signals are transmitted to the A/D converter to be changed into digital signals after the programmable bandpass filter gets rid of the interference signals, then the digital signals are transmitted to the CPU to be processed and complex impedance of the storage battery under the corresponding frequency can be obtained after arithmetical operation. The CPU can control the MOS tube via the D/A converter to change the waveform and frequency of the discharge current of the storage battery so as to realize measuring a plurality of frequencies of the storage battery. A detecting method using the device can be used for detecting the storage battery by an AC discharge method in multiple frequency points.