The invention provides an energy-saving box type centrifugal fan. The energy-saving box type centrifugal fan comprises a mounting seat, an air inlet, open grooves, a dividing and combining mechanism,a buffering seat, a rotating motor, a driving wheel, a flat belt, a centrifugal mechanism, an air outlet, a box body, a bearing seat, a driven wheel and a positioning pin. Through arrangement of the centrifugal mechanism and the dividing and combining mechanism, the dividing and combining mechanism is pushed to drive a driven shaft to move leftwards to achieve sliding block type connection of a coupler. A driving shaft drives power to the driven shaft, and therefore a first centrifugal impeller and a second centrifugal impeller rotate at the same time, and the flow speed of air is improved. The two centrifugal impellers are adopted, so that the defect that the length of a box body behind the impellers influences the air sucking effect in the prior art is overcome. A rotating draught fan and the buffering seat is arranged, the buffering seat is additionally arranged at the bottom of the rotating motor, and therefore direct contact between the rotating motor and the box body is avoided,and vibration and noise during working are effectively reduced.