Abstract: The present invention discloses a biomass fuel internal circulation mechanical fluidized-bed corner tube intelligent boiler which is highly effective in energy-conservation and emission-reduction, which comprises a primary combustion chamber, a secondary combustion chamber, a burning-out chamber, a high temperature multi-tube cyclone dust collector, a heat convection pipe bundle, the hearth of the primary combustion chamber consists of a square membrane water-cooled wall and a profiled seat with a square top and a circular bottom, at the four corners of the seat, there are mounted Venturi tube internal circulators, at the bottom of the hearth, there is mounted a mechanical fluidizing machine; the profiled cyclone separation hearth of the secondary combustion chamber consists of a square membrane water-cooled wall, a profiled seat with a square top and a circular bottom, a profiled fume-venting tube, at the bottom of the hearth, there is mounted a mechanical fluidizing machine; the burning-out chamber is conne