SiS vapor is generated as a byproduct in the process of preparing metal silicides by silicothermic reduction of their metal disulfides, and the vapor will cause severe pollution without rational utilization. In this paper, an efficient method was proposed to prepare ultrafine SiS spheres and silica spheres. In the process of synthesizing molybdenum disilicide, yellow-orange SiS nanospheres with different sizes were prepared by rapidly condensing SiS vapor in different temperature zones. After SiS powders were roasted at high temperatures in air atmosphere, silica nanospheres were obtained. The shape and size of the obtained SiO2 particles remained almost the same as that of the SiS particles. X-ray diffraction, Fourier transform Raman spectrometry, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, dynamic light scattering measurement, etc. were used to characterize the products.