A new gas sensor was designed based on cataluminescence (CTL) by using catalytic reduction of benzene, toluene and xylene (BTEX) on the surface of nanosized catalyst Al2O3/Pt with hydrogen as the carrier gas. The result indicated that the sensor showed strong CTL response, high selectivity and excellent durability under optimal conditions: Al2O3/Pt (1%), the temperature of 395oC, the wavelength of 425 nm and the flow rate of 270 mL/min. The detection limit (3σ) is 0.2 ppm for benzene, 0.3 ppm for toluene and xylene. Other corresponding substances such as methanol, ethanol, formaldehyde, acetaldehyde, ethylacetate, ammonia and trichloromethane had no or less interference. It is a simple and convenient sensor with good selectivity and sensitivity for detecting BTEX.