Abstract: The scanning electron microscopy (SEM) is mainly used for the observation and analysis of morphology, structure, and composition of samples. The SEM possesses advantages in resolution, depth of field and ease of operation. It plays an important role and is widely used in materials, physics, chemistry, biology, geology, archaeology, microelectronics industry, etc. Based on our experience of operating the SEM, this paper introduces the fundamental principle, construction, advantages, and applications of the SEM, which is helpful for the SEM learner and operator to grasp and use the SEM.