The invention discloses a composite startup burner for a powder coal gasification furnace. The composite startup burner comprises an inner burner and an outer burner which are provided with a front necking end respectively and are coaxially sleeved from the inside to the outside, wherein a cooling water jacket adopting a single-spin mode is arranged on the periphery of the outer wall of the outerburner; the front end of the inner burner is provided with an ignition electrode; and the nozzle of the burner is provided with a supersonic atomization device. The composite startup burner adopts supersonic atomization to ensure that the burner has small fluctuations in fuel and atomization airflow rate, and a little change in outlet speed in a process that the back pressure rises continuously so as to ensure the atomization effect and high-temperature flame far from the head of the burner; the composite startup burner adopts a center ignition mode to save an ignition burner to realize the two-in-one function, and adopts a single-spin cooling mode to ensure that the head of the burner is protected from damage under the condition of high temperature and high pressure to prolong the service life of the burner.