The utility model relates to a temperature-controlled fan system with speed regulated by a mechanical stepless speed changer. The system comprises a water temperature sensor, an oil temperature sensor, an electric control unit, a mechanical stepless speed changer and a fan, wherein the electric control collects temperature signals of the water temperature sensor and the oil temperature sensor to control the mechanical stepless speed changer, and then the mechanical stepless speed changer regulates rotational speed of the fan. The temperature-controlled fan system has the beneficial effects that the system uses the mechanical stepless speed changer as a drive element of the fan, so that the speed ratio of the mechanical stepless speed changer can be controlled according to signals such as engine water temperature, hydraulic oil temperature and the like, and then the fan works at the needed rotational speed; and the system saves energy, has low noise, is more suitable for surrounding environment, and can greatly shorten pre-heating time of the machine in regions with large temperature difference between day and night or northern cold regions.