A fabricating system of fiber tapers using a CO<sub>2</sub> laser as its heat source has been developed. According to the self-regulating effect of the CO<sub>2</sub> laser in the process of melt-drawn fiber, the relation between the required CO<sub>2</sub> laser power and the moving distance of the motorized stage in the fabrication process of fiber taper is found. The dependence of the required laser power and the moving distance of one motorized stage running is of approximately linear increment, which largely simplifies the computer control. With the relation plus regulating the other parameters, a 1.3 μm diameter fiber taper is fabricated. The tapers fabricated by our system have good shape and size for optical device applications.