The invention provides a low-nitrogen combustion device for a cement kiln tail. The low-nitrogen combustion device comprises two combustion device bodies which are symmetrically arranged on a conicalpart of a decomposing furnace, one combustion device body is arranged below an inlet of a tertiary air pipe and close to a reducing position, and the other combustion device body is arranged on the opposite side of the tertiary air pipe; each combustion device body comprises a connecting sleeve connected to the decomposing furnace, a pulverized coal nozzle, a rotatable air guide blade, an air guide blade sleeve, an adjusting end cover and the like, the rotatable air guide blades adjust the flow of a mixture of pulverized coal and air according to actual production requirements, excessive pulverized coal injection is avoided, fuel consumption is reduced, meanwhile, crusting of the inner wall of the decomposing furnace is reduced to a certain extent, and the service life of equipment is prolonged; nitrogen oxide formed by high temperature in a kiln is reduced through reducing atmosphere generated by oxygen-deficient combustion of the pulverized coal, nitrogen emission is reduced, and therefore the purposes of energy conservation and emission reduction are achieved. The device is simple in structure, low in construction cost, low in requirement for installation space, particularly suitable for old system transformation and capable of effectively protecting the environment.