PURPOSE: A compact solid oxide fuel cell system is provided to save costs and to minimize energy waste by reformed air and steam through a heat exchange type catalyst burner and a waste heat steam generator to an autothermal reformer by switching paths of air and water. CONSTITUTION: A compact solid oxide fuel cell system comprises: a stack(10) for generating electricity through an electric chemistry reaction of hydrogen and oxygen which are respectively supplied to a fuel anode(11) and an air electrode(12); a heat exchange type catalyst burner(30) which discharges waste heat to the outside through combustion of tail gas and used air and supplies the combustion heat to the air electrode by heating process air; a burner(40) for supplying reformed air to an autothermal reformer; and a steam generator(50) for supplying steam to the autothermal reformer.
