A new type of SnO2/SnCl2 semiconductor as detector in gas chromatography has been developed. The sensing crystalloid with SnO2 as main block has an outstanding sensitivity to the reducing gases in a certain oxidative circumstance. The reducing gases can be reversibly adsorbed on the surface of crystal and make the resistance of the sensing element changed. Therefore, this type of sensing element may be used as detector in GC. We studied and prepared such sensing element with SnCl2 as catalyst to improve the sensitivity. An optimum procedurefor preparation has been received. We also discussed the possibilily as the gas-sensing element to replace the flame ionization detector in GC. The results showed that at the condition of 300 degrees C, the sensitivity, stability, detectability and linear range were satisfactory. This new type of detector can meet the needs of practical sample analysis.