The invention discloses a biomass environmental-friendly energy-saving steam boiler of a spiricle fire tube. The steam boilder is composed of a back combustion opening (1), a flame inlet (2), a flame outlet (3), a spiricle fire tube extruded edge (4), a spiricle fire tube (5), a water sleeve (6), an ellipsoidal end (7), a charging opening (8), a semi-gasification furnace chamber (9), a water grate (10) and a secondary combustion chamber (11), wherein the spiricle fire tube is welded in a furnace body vertically or horizontally, and the furnace body is sealed up and down with the flame inlet and the flame outlet remained; when in combusion, the flame enters the fire tube, is not discharged upward directly, but is guided by the extruded edge in the spiricle fire tube. The steam boiler provided by the invention has the advantages of full combustion, high heat utilization ratio, energy-conservation and emmission reduction and favarable economic benefit, and is easy to popularize and implement.