The invention relates to a self-heating heater. A light source or a power supply is needed when drinks or foods are heated during outdoor activity, which is very inconvenient. The self-heating heater comprises a tank body (2), a tank cover (1), a heat-resistant rubber seal ring (4), a heating substance (7) and water (6). The inside of the tank body (2) is divided into two cavities used for containing the heating substance (7) and water (6) respectively, when being placed in a container (10) containing drinks or liquid foods, the self-heating heater turns over laterally or is inverted due to the designed shape or internal structure, the heating substance and the water flow out and are mixed to generate reaction to produce heat, and the heat energy is transmitted to the foods or drinks in the container (10) through the outer metal shell of the self-heating heater so as to heat the foods or drinks. By using the self-heating heater in the invention, the drinks or foods can be heated conveniently when no heating equipment is provided in the open air. The self-heating heater has no strict requirement on the shapes of the container containing the drinks or foods, has low cost and certain popularization effect, and is simple to operate.