Laser speckle contrast imaging (LSCI) is a non-scanning optical imaging technique with wide field of view for monitoring blood flow velocity. LSCI technology has advantages of high temporal-spatial resolution, fast real-time imaging, non-contact, simple structure, and no contrast agent. Here we briefly introduced the basic principles of LSCI, structures of reflective-detected LSCI and transmissive-detected-LSCI. In addition, this paper reviewed the latest research progress of LSCI in biomedical applications such as skin blood flow, cerebral cortex and retinal blood flow, and makes further prospects for its development, provide theoretical basis and practical guidance for blood flow monitoring.