A new method for detecting the infection of Helicobacter pylon (HP), '5N-urea tracing and emissive optical spectroscopy method, is described in this paper. A group of 26 patients was tested. After '5N-urea was administered orally, urine specimen was collected from 30 to 120 minutes and its volume was measured. Then the concentration of ammonia in the urine specimen was determined. A special emissive optical spectrometer was applied to measure the '5N-abundance ofthe urine specimen, which was designed and manufactured by us and was an intelligent system. It contains a monochromator, a high frequency generator, a precise amplifier and a computer. The ratio (R) of the 15N amount of excretion in the urine to that of ingestion was found out. HP positive infection was predicated if R>0.3%. Taking the bacterial culture or (and) Gram stain as a reference standard, the specificity, sensitivity and positive predictability ofour test were 81%, 89% and 84% respectively. The new method is sensitive, noninvasive and useful for clinical practice. It is worth studying it further.