The invention relates to an ultraviolet sterilization device. The device includes an ultraviolet modulator tube (1) capable of emitting ultraviolet light and a sterilization cavity matched with the ultraviolet modulator tube (1) and capable of sterilizing water flowing through the inner cavity of the sterilization cavity. The device is characterized in that the device also includes an organic matter detection sensor used for detecting the organic matter content of water; the organic matter detection sensor includes a detection assembly cooperated with the ultraviolet modulator tube (1) and capable of detecting the organic matter content of the water; and the detection assembly includes a detection tube (2), a detection-group ultraviolet light receiver (3) and a circuit board (4). Compared with the prior art, the device is advantageous in that by utilizing the ultraviolet light emitted by the ultraviolet modulator tube and through setting the detection-group ultraviolet light receiver and the circuit board, the organic matter content of the water flowing through a sterilization tube is acquired through the intensity of the ultraviolet light received by the detection-group ultraviolet light receiver, and therefore the device has a sterilization function and an organic matter content detection function.