The invention discloses a device and a method for simulating the electrochemical corrosion of concrete reinforcement caused by stray currents. The device comprises a power supply, a constant potential rectifier, a liquid trough, a reference electrode, an auxiliary anode and a sample, wherein the liquid trough is filled with electrolyte, the reference electrode, the auxiliary anode and the sample are soaked in the electrolyte, the sample is a concrete block pre-buried with a rebar, the power supply comprises a signal generator and a bipolar direct-current power supply, a stray current analog signal generated by the signal generator is transmitted to the bipolar direct-current power supply, and a voltage signal output end of the bipolar direct-current power supply is connected with a signal input end of the constant potential rectifier; a reference electrode interface of the constant potential rectifier is connected with the reference electrode, a working electrode interface of the constant potential rectifier is connected with the rebar on the sample, and an auxiliary anode interface of the constant potential rectifier is connected with the auxiliary anode. According to the device, the simulation test for electrochemical corrosion to the rebar in a reinforced concrete structure in a subway tunnel in the presence of the stray currents under laboratory conditions; the method can be applied to the mechanism research on the corrosion of the stray currents to the rebar.