An upper gastrointestinal bleeding monitoring system, which is composed of a detection device and a signal processing device, is provided to determine bleeding condition of an upper gastrointestinal tract by using relation of time and intensity ratios of RGB three primary colors. The detecting device is placed to the upper gastrointestinal tract of a patient via his/her mouth or nasal passage and then stay the upper gastrointestinal tract for several days for detection of bleeding. The signal processing device may receive and display signal from the detection device to help medical professionals check if bleeding occurs in an upper gastrointestinal tract. Moreover, a procedure of determination of bleeding in an upper gastrointestinal tract with the upper gastrointestinal bleeding monitoring system is described.
