The invention relates to an optic travelling wave cavity enhanced laser raman gas concentration detection device. The device combines a cavity enhanced technology with a laser raman detection technology, and utilizes an optic traveling wave passive cavity; a single curved-surface annular internal reflector forms a high-fineness cavity, and a laser outgoing beam oblique incidence cavity enhanced principle is utilized, so that laser beam is reflected in the cavity for many times and is propagated in a travelling wave manner, the laser beam passes through gas to be detected in an area to generate raman scattering, raman scattered light is collected by a photoelectric detection component after being gathered with the laser beam through a filter plate, and the photoelectric detection component detects the raman frequency shift and the corresponding raman peak intensity of the characteristics of the gas to be detected to obtain the concentration of the gas to be detected. The detection device disclosed by the invention has the characteristics of simple structure, low requirements on mechanical location, good stability and high reliability; meanwhile, the anti-jamming performance of the detection device is improved; the detection device can measure on line in real time to increase the dynamic information of the process and can detect the concentration of nearly all gas, except inert gas; the sensitivity is high; the response speed is high and the response time is short.