An outdoor umbrella includes an umbrella frame and an audio system. The umbrella includes a supporting frame and an awning frame supported by the supporting frame to define a shadowing area under the awning frame. The audio system includes at least a speaker unit supported by the umbrella frame and an audio input operatively linked to the speaker unit such that when the audio input sends an audio signal to the speaker unit, the speaker unit is adapted for producing audio effect within the shadowing area as an additional function for the outdoor umbrella.