The invention discloses a wood crushing device for papermaking. The wood crushing device comprises a shell, a feeding hopper, a dustproof mechanism, a primary crushing mechanism, an extruding and crushing mechanism and a collection groove, wherein the primary crushing mechanism is arranged at the upper end of the inner side of the shell; the primary crushing mechanism comprises a crushing roller,a motor, a first sieving plate, a sliding rail, an eccentric wheel and a second rotating rod; the extruding and crushing mechanism is arranged below the primary crushing mechanism; the extruding and crushing mechanism comprises a bidirectional thread rod, side plates, a second sieving plate, a sleeve, a crushing blade and a rotating shaft. The wood crushing device disclosed by the invention is novel in design; the dustproof mechanism can be used for effectively preventing wood dust generated in a wood crushing process from flying out to lead the environment influence; when the bidirectional thread rod rotates, the two side plates are driven to do face-to-face movement or opposite-direction movement; when the side plates do face-to-face movement, wood blocks at the inner sides of the side plates can be pressurized and gathered toward the middle, so that the crushing effect of the wood blocks is improved.