Based on the characteristic of spectrum absorption of CO

a set of optical fiber detection system with reference gas cell is designed

which has reference channel and is for on-line and real-time detection.Two wavelength differential absorption measurement is used to eliminate the interference owing to various disturbances

such as light power

optical fiber

sensor head changing

thus the sensitivity is improved.Some experimental results are presented.Results show the sensor has many characteristics such as simple structure

small size

stable performance and high anti-jamming.It is possessed of wide application area.