The invention relates to the technical field of grinding devices and discloses a material crushing and mixing device. The material crushing and mixing device comprises a bottom plate and a grinding barrel. Supports are arranged in the positions, located at the two ends of the grinding barrel, on the bottom plate correspondingly and are provided with rotary seats. A left support shaft and a right support shaft are connected with the rotary seats rotationally in a one-to-one correspondence mode. The bottom plate is provided with a motor connected with a right rotary shaft. The side face of the grinding barrel is provided with a feed inlet. Sliding plates are arranged at the left end and the right end in the grinding barrel correspondingly. A thread sleeve is arranged in the center of each sliding plate. A transmission shaft is arranged in the axial direction of the grinding barrel and is provided with two segments of threads with opposite rotary directions. The two segments of threads are connected with the thread sleeves on the two sliding plates in a one-to-one correspondence mode. The left end of the transmission shaft penetrates through the left support shaft to extend out of the grinding barrel. The bottom plate is provided with a support seat provided with an auxiliary motor. A clutch mechanism is arranged between the auxiliary motor and the transmission shaft. In the material crushing and mixing device, the volume of the grinding barrel can be adjusted and changed, and the best volume ratio of a grinding ball and the grinding barrel can be obtained through tests.