The invention discloses a machining and compacting device for cement boards. The device comprises a working table, three groups of supporting columns are arranged on the back surface of the working table, and a concave fixing base is fixedly arranged at the position, close to the top positions, of the front surfaces of the three groups of supporting columns; and two sets of hydraulic cylinders areoppositely arranged on the two sides of the top end of the fixing base, inner piston rods of the two sets of hydraulic cylinders penetrate through the fixing base and are in transmission connection with a pressing plate, an auxiliary compaction mechanism is arranged at the bottom of the working table, and a material storing mechanism is arranged at the top of the working table. The machining andcompacting device of the cement boards is provided with the auxiliary compaction mechanism and the material storing mechanism, and the cement boards are recompacted in a vibration mode after the compaction of the pressing plate is completed, so that the machining effect of the cement boards is improved; and meanwhile, through the assembling structure between an upper mold and a lower mold, the boards can be conveniently taken down after machining of the boards is finished, so that a better practical prospect is brought.