Tb3+-doped silicate scintillating glass was made by high temperature melt-quenching method and the energy response to hard X-ray (from 5 to 80 keV) was measured. The response of photocurrent of silicate scintillating glass to X-ray (with various energy) is nonlinear. It was noted that the change in nonlinearity around 8 and 50 keV is obvious. This phenomenon is concerned with the production of abundant electrons when the scintillating glass absorbed X-ray and the energy response of scintillating glass to electrons.