The invention provides a double-direct-current circulating fluidized bed steam injection boiler with buried pipes and evaporation coils, and belongs to the technical field of oil field steam injection boilers. The problem that heat transformer deterioration and pipe explosions can be caused when the inner walls of water-cooling wall pipes are prone to salt scale for a long time in existing natural circulation oil field steam injection boilers is solved. The buried pipes are arranged in a low-speed bed in a furnace body. The evaporation coil is wound around the inner circumferential side wall of the furnace body to form a hearth water-cooling wall. The evaporation coil is communicated with upper collection boxes which are communicated with a steam-water separator in a steam pocket. Steam-water separation is conducted on a steam and water mixture entering the steam pocket through the steam-water separator, water which is separated out enters water space of the steam pocket, steam which is separated out enters steam space of the steam pocket, the water space of the steam pocket is communicated with an evaporator, the evaporator is communicated with an external centrifugal separator through a fourth connection pipe, the external centrifugal separator is communicated with a mixer through a seventh connection pipe, the superheated steam outlet of a superheater is communicated with the mixer, and the steam space of the steam pocket is communicated with the air inlet of the superheater. The double-direct-current circulating fluidized bed steam injection boiler is used for oil field steam injection.