Optical coherence tomography (OCT) is a new medical imaging technology that developed at the end of the 20th century after X-ray, computed tomography (CT), magnetic resonance imaging (MRI), and intravascular ultrasound (IVUS). It is called “optical biopsy” technology with the advantages of no radiation, simple structure and high resolution that can reach ten times that of IVUS. However, OCT also has the disadvantage of insufficient depth of detection that only a few millimeters and imaging speed. Even so, OCT can be used in combination with microscopes, medical catheters and endoscopes; therefore, it has broad application prospects in the field of biomedicine. The OCT system is simple in structure, mainly Michelson interferometer. Using the principle of optical coherence imaging, it detects the back-reflecting or scattering signals of incident light at different depths of biological tissue to obtain the surface and subsurface imaging of transparent or opaque substances. The combination of OCT and endoscopy extends the use of OCT to the diagnosis of cardiovascular diseases, which is called intravascular optical coherence tomography (IVOCT). It enables rapid visualization of microscopic images of vascular cross sections and is a powerful tool for clinical detection of coronary atherosclerosis, in which coronary artery calcification is a common problem in the clinic and is closely related to cardiovascular diseases. This review will briefly introduce the principle of OCT technology and its application in cardiovascular diseases, and focus on the research progress of detection of coronary artery calcification based on OCT technology.