The utility model relates to a coffee maker capable of preventing steam backflow. The coffee maker comprises a grinding unit, a guide unit and a brewing unit. The grinding unit is used for grinding coffee beans. The guide unit is used for discharging coffee particles after grinding. The brewing unit is used for brewing the coffee particles with high temperature. A section of guide tube extends from one end of a container for containing coffee particles. The container is located at the lower end of the grinding unit. The outlet of the guide tube corresponds to an opening on one side of a top covering part of the brewing unit. A gear motor is disposed at a preset position of the top covering part of the brewing unit. A cover is disposed at the axis of the gear motor. When the coffee particles from the grinding unit are guided into the brewing unit along the guide tube and reach a preset amount, the gear motor drives the cover to shift so as to close the opening at the top end of the brewing unit. Since the gear motor can drive the cover to shift so as to close the opening at the top end of the brewing unit, high-temperature steam can be prevented from entering into the grinding unit along the guide tube to soak the remained coffee particles.