A negative pressure wound therapy system with exudate level detection through photoelectric total internal reflection, includes: a negative pressure wound therapy device a fluid collection canister for collecting exudates, where a side wall of the fluid collection canister protrudes outward to form a protrusion, an angle θ formed by two planes where two opposite sides of the protrusion are located respectively is greater than 97.2 degrees and smaller than 180 degrees and at least one detecting module, including: a transmitting unit arranged at one side of the protrusion a receiving unit arranged at the other side of the protrusion and a detection control unit, adapted to determine, according to a determination of whether the receiving unit receives the electromagnetic wave or ultrasonic wave signal transmitted by the transmitting unit, whether there exit exudates where the detecting unit is located.
