The utility model discloses a digital image natural gas water dew point detector. The digital image natural gas water dew point detector comprises an air cavity (1), a cooling mirror (3) in the air cavity (1) and a temperature sensor (5) in the air cavity (1), wherein the air cavity (1) is communicated with a natural gas filling station through a pressure transmitter (2). The digital image natural gas water dew point detector has the structure characteristics that a cooling end (4a) of a semiconductor cooling plate (4) is arranged in the air cavity (1); a heat end (4b) of the semiconductor cooling plate (4) is positioned outside the air cavity (1); a camera (6) and an LED light (7) are arranged in front of the cooling mirror (3) inside the air cavity (1); the pressure transmitter (2), the temperature sensor (5) and the camera (6) are connected with a data processing and controlling unit. The water dew point detector is easy to operate, small in detection errors, and accurate and reliable in detection result; moreover, traceable experimental evidence can be left, and automatic quality control of the natural gas filling station is conveniently carried out.