The invention relates to a quenching method for bottoms of narrow-grooved components and a special device. The method and the device are used for quenching bottom faces of grooved components while the sidewalls and edge openings of grooves are not subjected to quenching. The method comprises the technical key point that a main body of a heater is buried in water, and the upper surface of the heater is exposed to a water surface; groove openings of grooved workpieces face downwards, the sidewalls of the workpieces are buried in water, and the bottom faces of the workpieces are located at corresponding positions on the upper surface of the heater; and then, the heating and quenching are carried out. According to the method and the device, the main body of the heater and main bodies of the grooved workpieces are located in water so as not to be heated, and only the bottom faces of grooves are subjected to heating and quenching, so that the requirements of a groove bottom face quenching process can be met, other positions of the components cannot be heated at the same time, and then, the performance of the workpieces cannot be affected. Due to the slight flowing of water, the water temperature can be reduced, so that the influence on the workpieces caused by the fact that water around the heater is evaporated due to heating is avoided.