Abstract: A new chemical vapor deposition method was proposed to prepare carbon-based SnO₂ micro/nanospheres with different particle sizes. The method has the merits of low equipment requirements, easy operation, and low cost. The prepared SnO₂ micro/nanosphere has good sphericity, high surface smoothness, wide and continuous distribution of particle sizes in the range of 20 nm~3.3 μm, along with good stability under vacuum and electron beam bombardment, good electrical conductivity, high secondary electron yield and wide distribution of particle sizes in scanning electron microscopy. It is especially suitable for calibration of image resolution, astigmatism, and imaging quality of scanning electron microscope in 2~50k magnification.