A projector includes a lamp, a fan for dissipating heat generated by the lamp, a housing, a number of blades received in the housing, and a elongated-slider. The housing receives the lamp and the fan, and includes a top cover, a sidewall connected to the top cover, and a bottom cover connected to the sidewall. The top cover defines an through opening therein. The blades can be rotated in cooperation with the slide of the elongated-slider in the through opening. As described above, the projector can exhaust thermal formed by the lamp or electronic elements from the air outlet. At the same time, the flow direction of the air from the air outlet can be changed in cooperation with the slider. Therefore, when a user sits by the air outlet, the user can adjust the flow direction of the air from the air outlet at any time.