In this paper, catalytic combustible gas sensor was fabricated and tested under flammable gases such as CH$_4$and $C_4$H$_{10}$by using Pt coil as a heater and/or temperature sensing element. Fine $Al_2$O$_3$powder was used for a bead and Pt, Pd noble metal powder for a catalyst. Resistance variation of Pt wire was traced by the changes of the gas concentrations in a chamber. Output voltage was then monitored to obtain the gas concentration from the resistance variation. In this experiment, MgO was used to protect cracks in the based and TiO$_2$to increase the sensitivity of the sensors. Water glass was also added to enhance the selectivity to the combustible gases.s.