In this paper, the passivation effect of Au nanoparticles (AuNPs) on the focused electron beam (e-beam) irradiation-induced nonuniform structure changes of amorphous SiOx nanowire (a-SiOx NW) is in-situ investigated at room temperature in a transmission electron microscope. It is found that the pristine a-SiOx NW demonstrates an accelerated necking at the nanoscale along with a fast, plastic elongation and a local S-type deformation in the axial direction. However, when the surface of a-SiOx NW is modified with uniform AuNPs, it becomes remarkably passivated and the processing transfers from a diffusion (or plastic flow)-dominated status to an evaporation (or ablation)-dominated status. As a result, the necking of the AuNPs-modified a-SiOx NW is greatly retarded with a much lower shrinking rate and there is no visible elongation and bending deformation observed. Further, the combined effects of nanocurvature and beam-induced soft mode and instability of atomic vibration are applied to elucidate the observed new phenomena.