The thickness of the central cornea has an important influence on various eye diseases and operations such as keratoconus and other corneal diseases, glaucoma, and corneal refractive surgery. Obtaining accurate central corneal thickness is a topic that clinicians have been paying close attention to. It decides the operation method and operation parameters(cutting depth, cutting optical area size, etc.)of refractive surgery. Accurate measurement of central corneal thickness is a great concern to clinicians. At present, there are two kinds of measurement of corneal thickness: the first is ultrasonic measurement, such as traditional Type A ultrasonic corneal thickness meter and ultrasonic biological microscope; the second is optical measurement, including Pentacam, corneal endokeratoscope, optical coherence tomography, etc. Different measuring methods and instruments have their own advantages and disadvantages. However, the ultimate goal of developing corneal thickness measurement is easy operation and good repeatability. Therefore, based on the summarization of current clinically-used corneal thickness measurement instruments and of research progress of corneal thickness measurement, this paper aims at providing theoretical guide for clinical oculists.