Diabetic retinopathy and diabetic nephropathy are the two most common and serious microvascular complications in diabetic patients, and they are the main causes of blindness and end-stage renal disease. Retinal blood vessels are the common damage targets of early diabetes and the only living blood vessels in the human vascular system that can be directly observed in naked eye. The changes in their morphological structure or function directly or indirectly reflect the microvascular lesions caused by diabetes. Especially, in recent years, the development of optical coherence tomography angiography(OCTA), a new and non-invasive technology, has made its breakthroughs in angiography resolution, vascular depth and vascular morphology, and it can provide objective quantitative data. It has certain application value in diabetic microangiopathy. Therefore, the purpose of this paper is to review OCTA and its application in diabetic microangiopathy.