A cooling system of a thin projector, and a method for controlling the same are disclosed. The system comprises a heat source 1 in a housing, first and second suction ports formed at side and lower surfaces of the housing, respectively, a discharge port formed at an upper surface of the housing, first and second air stream forming units 2 and 3 to form first and second air stream along which air induced from the first and second suction ports is guided to the discharge port while cooling the heat source, respectively, a sensor unit to detect a temperature of suction air induced from the first and second suction ports and a temperature of discharge air discharged from the discharge port, and a controller 6 to control the first and second air stream forming units 2 and 3 using the temperatures of the suction and discharge air.