A coffee grinder includes a machine base, in which a crushing unit, a separating unit, and a grinding unit are provided. The machine base has an inlet and an outlet, and the crushing unit is under the inlet to crush coffee beans into parchments and beans. The separating unit has a rotary member and a collection container that the rotary member provides an air flow to send the parchments to the collection container. The grinding unit is between the crushing unit and the outlet to grind the beans from the separating unit and send the ground beans to the outlet. The present invention crush the coffee beans to separate the parchments and the beans, and the parchments are removed by the separating unit. Next, the beans will be ground.