The invention discloses a concrete mixer which comprises a rack (1), wherein a material cylinder (2), a sandstone feeding port (3) and a cement feeding port (4) are mounted on the rack (1); each shaft I (5) is mounted in the material cylinder (2) through two corresponding bearings I (6); feeding plates A (8) and feeding plates B (9) are mounted below blades (7); a water spraying structure comprises a water pipe (20) and a spraying head (21); a gear box (10) is arranged on the material cylinder (2); a bevel gear A (13) is mounted on the stirring shaft (11); a shaft II (16) is mounted on a side surface of the gear box (10) through a bearing II; a bevel gear B (15) is mounted on the left side of the shaft II (16); the middle part of the shaft II (16) is mounted on the material cylinder (2) through a bearing III; a belt wheel A (17) is in belt connection with a belt wheel (18) of a motor (19); stirring blades (23) are mounted on a stirring shaft (11); and a top bearing (14) is mounted at the top of the stirring shaft (11). The concrete mixer is simple in structure, convenient to operate, uniform in stirring, and rapid and convenient in discharging.