The invention discloses a pulp quantitative extruding device for solid thrust engine charging. The device comprises a first pipe clamping valve 2, a quantitative rubber pipe extrusion pump 1 and a second pipe clamping valve 15 connected in sequence. The device further comprises a second rubber pipe 42 and a third rubber pipe 43; the quantitative rubber pipe extrusion pump 1 can extrude a first rubber pipe 41 to an appointed collecting state or pull the first rubber pipe 41 to recover to a natural state; the first rubber pipe 41, the second rubber pipe 42 and the third rubber pipe 43 communicate; and the first pipe clamping valve 2 and the second pipe clamping valve 15 sleeve the second rubber pipe 42 and the third rubber pipe 43, and are used for extruding or pulling away the second rubberpipe 42 and the third rubber pipe 43. In the device, pulp is only extruded with the rubber pipes during extruding, so that the process is safe and reliable; the extruding quantity is adjustable; andthe quantifying consistency is better to achieve automatic production.