An energy-saving compact vacuum extruder, which includes a reducer (1), a pneumatic clutch (2), a slider coupling (3), an extrusion shaft (19), a driving gear (15), a driven gear (5 ), gear (6), active stirring shaft (4), passive stirring shaft (26), Huff mixing knife (8), vacuum chamber (11), mud pressing plate (12), extrusion cylinder (13), machine Head (14), extrusion auger (21), upper, middle and lower casing (22), (23), (25), support (24) and hopper (7); Its key is: power machine (18 ) output shaft pulley (17) drives the pneumatic clutch pulley (2) located at the input shaft end of the reducer (1) through the transmission belt 16, and the output shaft of the reducer drives the extrusion shaft (19) through the slider coupling (3) Rotation; at the same time, the driving gear (15) mounted on the rear of the extrusion shaft drives the passive gear (5) to rotate the active stirring shaft (4), and the passive stirring is driven by the coaxial gear (6) with the driving gear (15) Axle (26) relatively rotates. The invention changes the deficiency of multiple motor drives and high energy consumption of the current two-stage vacuum extruder, optimizes the transmission mode, reduces mechanical friction, and achieves the purpose of high efficiency and energy saving.