The invention provides a reinforced concrete structure durability repairing method and device capable of synchronously desalting and repairing cracks. The reinforced concrete structure durability repairing device comprises a water tank, wherein the water tank is arranged around a to-be-repaired area of a concrete structure, waterproof sealing structures are arranged at connecting edges among the different water tank faces of the water tank and at the connecting edges of the water tank and the concrete structure, an electrolyte solution which is higher than the to-be-repaired area is added into the water tank, the electrolyte solution is magnesium salt or zinc salt with mixed phosphate as the pH buffer, reinforcing steel bars in the cracks of the to-be-repaired area are used as cathodes, a stainless steel mesh is arranged along the inner wall of the water tank to serve as an anode, and the cathodes and the anode are respectively connected with the cathode and the anode of a constant-current power supply through cables. The reinforced concrete structure durability repairing device has the advantages that the device is used for reinforced concrete beams and columns which are not in water, the chloride ions in concrete can be removed while the concrete cracks can be repaired, desalting and crack repairing are performed synchronously, and the defect that a process which needs to repair the cracks before desalting is long in construction period is overcome.