The feed inlet structure for biomass fuel boiler includes one upper inclined fuel feeding structure comprising one fuel feeding pipe in certain angle to the front hearth wall and one outwards wideningpart below the fuel feeding pipe; one lower secondary air pipe structure comprising one secondary air pipe and several secondary air nozzles inserted into the outwards widening part and fixed to thesecondary air pipe; and one regulating mechanism comprising one cooling air pipe, one regulating baffle and one regulator to control the rotation of the baffle. The feed inlet structure feeds fuel into the boiler homogeneously, cools the feed inlet and realizes the efficient clean burning of the biomass fuel.