Brush with liquid in it

The utility model discloses a brush with stored liquid which can be extruded in a controllable mode for painting. The utility model is composed of a brush holder and a brush head, wherein, a piston is arranged in an inside hollow cavity of the brush holder, a piston rod is arranged on the piston, a rack bar and a gear wheel matched with the rack bar and fixed on the brush holder are arranged on the piston rod, and partial gear wheel is exposed outside; a slide valve is arranged in a cavity body which is positioned in the brush head and is communicated with the hollow cavity in the brush holder; a spring is arranged between the slide valve and the brush head, and the slide valve can be in two states that the hollow cavity and a liquid discharge passage are communicated or intercepted. When the piston is pushed, the liquid can be discharged through the liquid discharge passage. The utility model has the advantages that the liquid flow is convenient for control, and the painting is convenient.