The azo benzene(Azo) doped polyvinylpyrrolidone(PVP) composite film was immobilized on the surface of potassium ion(K+) exchanged glass optical waveguide(OWG) by spin coating method.An Azo-PVP compound thin film/K+ exchange glass optical waveguide gas sensor was developed and its gas sensibility was investigated.The experimental results showed that the present gas sensor has a good sensibility to low concentration of styrene vapor at room temperature,and its response time and recovery time for 1.0×10-8 volume fraction of styrene gas were 9 s and 24 s,respectively.A good linear relationship was obtained between the output light intensity and volume concentration in the range of 1.0×10-8-1.0×10-3.The Azo-PVP composite film optical waveguide gas sensor has a short response time,high sensitivity,simple structure and easy farication.