The invention discloses a method and a device for pumping particle bentonite. The method comprises the following steps: (A) the particle bentonite is poured into a feeding tank; (B) a pumping valve isopened; a sucking valve is closed; and a piston rod moves up and down; (C) along with up-down movement of the piston rod, lubricating oil is extruded from lubricating oil boxes on the two sides of adischarge tank; (D) after the discharge tank is fully filled with the bentonite, the piston rod is downwards pressed; (E) a middle vibrator and a discharge port end vibrator are opened; and (F) the sucking valve is opened; and the pumping valve is closed. The feeding tank and the discharge tank are connected through a sucking pipe; the piston rod is embedded into a piston; the discharge tank is connected with a pumping discharge pipe; the pumping discharge pipe is connected with a single-section discharge pipe; the single-section discharge pipe is connected with a single-section discharge pipe; and the tail end of the single-section discharge pipe is connected with the end vibrator. The method is easy to realize and convenient to operate, and needs no heavy mechanical force for compaction.The device is simple in structure and convenient to use, can use an atmospheric pressure effect for uniformly and densely filling bentonite particles in grooves in underground diaphragm walls, and islow in cost and convenient to construct and operate.