The invention discloses a solar air heater and a working method thereof. The air heater comprises a solar energy collecting device and an indoor fan; a plurality of solar heating pipes are installed in the solar energy collecting device; each solar heating pipe comprises an outer pipe and an inner pipe, the inner wall of the inner pipe is coated with a selective absorbing coating, and a vacuum cavity is formed between the inner wall of the outer pipe and the outer wall of the inner pipe; and cold air feeding pipes are arranged in the inner pipes, one end of the cold air feeding pipes extend tothe bottoms of the inner pipes, the multiple cold air feeding pipes all communicate with an air conveying pipe, and the inner pipes are provided with hot air outlets. According to the solar air heater and the working method thereof, solar energy is converted into heat energy through the solar energy collecting device arranged outdoors, air is heated, then, heat conduction oil is heated through the hot air, finally, indoor air is heated through the heat conduction oil, and in the process, by adjusting the flow rate of the heat conduction oil and the rotation speed of the air, the air speed ofthe indoor fan and the temperature can be flexibly adjusted.