A liquid perfume diffuser includes a perfume bottle holding a liquid perfume, an inner cap threaded onto the perfume bottle, a rotary cover rotatably capped on the inner cap for pressing and rotating by the user to move the inner cap relative to the perfume bottle between a close position and an open position, so that when the perfume is opened, the liquid perfume can then be absorbed by a liquid-absorbing material in the rotary cap, enabling the pleasant smell of the liquid perfume to be slowly and naturally released into the outside open air through a capillary effect.
