Abstract: A set of scanning transmission electron microscopy (STEM) imaging device suitable for FEI Quanta 650FEG scanning electron microscope (SEM) was designed by using the back-scattering electron detector (BSED) of the SEM as the transmission-scattering electron detector, and the operation instructions of the STEM imaging device were formulated. The practicability of self-made STEM imaging device was verified by using halloysite composite ZrO₂ nanoparticles as the observation sample. The results show that the contrast of STEM image is related to the distance between the BSED and the sample. By adjusting the distance between the BSED and the sample, the high-angle annular dark field (HAADF) image can be collected, and the brightness of ZrO₂ nanoparticles is significantly higher than that of halloysite. The contrast of STEM image is consistent with HAADF-STEM image acquired by transmission electron microscope (TEM), and the distribution state of elements is also corresponding to halloysite and ZrO₂ nanoparticles, indicating that the STEM imaging device has good practicability.