The invention discloses a temperature control system for battery packs. The temperature control system for the battery packs comprises the battery packs, an ECU (electronic control unit), a constant-temperature tank filled with insulated oil liquid, an oil liquid filter, a radiator, a heater, an oil pump controller and an oil pump. The constant-temperature tank is provided with an oil outlet and an oil inlet, a plurality of temperature sensors are arranged on the surface of the constant-temperature tank, the temperature sensors, the radiator, the heater and the oil pump controller are respectively electrically connected with the ECU, the oil pump is connected with the oil pump controller, the oil liquid filter is respectively communicated with the oil outlet of the constant-temperature tank and an oil inlet of the oil pump through pipelines, an oil outlet of the oil pump is communicated with the radiator through a pipeline, and the heater is respectively communicated with the oil inlet of the constant-temperature tank and the radiator through pipelines. The temperature control system for the battery packs has the advantages of simple structure, low cost, high safety and the like, the temperature of the battery packs can be constantly controlled within a normal working temperature range, working efficiency of the battery packs is effectively improved, and the service life of the battery packs is effectively prolonged.