The invention provides a coffee machine bean grinding device and a coffee machine. The coffee machine bean grinding device comprises a machine body, a material box arranged on the machine body, a discharging device arranged in the machine body and used for controlling the material box, and a weighing device, a grinding device, a conveying device and a brewing chamber which are sequentially arranged at the lower end of the discharging device, and the brewing chamber is connected with a liquid outlet nozzle. The rotating shaft rotates in the discharging cavity, coffee beans are released throughthe storage space between the fan plates, the feeding speed of the coffee beans is controlled, and the situation that a large number of coffee beans inrush, and consequently the grinding amount is toolarge is avoided. Coffee beans discharged from the discharging device enter the weighing cylinder, the discharging valve channel is closed, the pressure sensor monitors the weight of the coffee beansin the weighing cylinder in real time, after the specified weight is reached, the system closes the discharging device, and the discharging valve channel is opened to release the coffee beans to enter the grinding device; and the discharging device and the weighing device are matched with each other, so that quantitative feeding of coffee beans can be realized, the grinding amount of the coffee beans is packaged, and the taste of coffee drinking is guaranteed.