Soft X-ray emission and its fluctuation in CT-6B tokamak are detected by using a Au(Si) surface barrier detectors array. The empirical scaling law for soft X-ray sawtooth oscillation in the center of plasma during internal disruption period is given in this paper. The electron thermal transport phenomena, such as electron heating rate, electron energy balance, electron energy confinement time, current density distribution, and electron temperature in the center of plasma during internal disruption are studied from soft X-ray sawtooth oscillation observations.