Abstract: Aiming to eliminate the need to use an external stir in most hot beverage cups, the present invention of a rotating cup mechanism includes: an outer cup, an inner cup and an outer cup base driving module while the inner cup is normally inset in the outer cup and interlocked with the driving module where the driving module leads to a push button exposed on the side. When the push button is repeatedly pressed, the driving module moves its gear wheel to start relative rotating motion between the outer and inner cups, generating liquid flows in the cup to achieve a more equilibrium mix of the liquid content. A secondary purpose of the present invention is the provision of a detachable inner cup that is can be easily removed for cleaning and then reassembled.