The reduction stage in the process of using NiO-YSZ of solid oxide fuel half-cell at 800 °C has been experimentally investigated. The analysis of the microstructure and the reduction degree of anode support materials have been addressed. As well as the residual stress variation of electrolyte film after different reduction times has been studied from which the full curve variation of the reduction degree with different reduction time has been obtained. It can be seen from energy spectrum that the mass fraction of oxygen decreases with the increase of reduction time and the minimum value is 13.24%, while the mass fraction of nickel increases with the increase of reduction time and the maximum value is 49.56%. It can be indicated from the X-ray stress analysis that the residual stress of the electrolyte film reduces gradually with the increase of reduction time. The value of the residual stress in the film reaches 394.35 MPa when the reduction time reaches 12 h, which accounts for 48.54% of the residual stress before reduction. It is revealed from the scanning micrographs that the porosity increases in the anode support materials after reduction.