Life is movement, so movement of molecular motors is essential for many life processes. Myosin, dynesin and kinesin are three important kinds of molecular motors, responsible for muscle and non-muscle cell movement. Sliding movement between myosin and actin is the molecular basis of muscle contraction. Kinesins and dyneins, which move directionally along microtubules, play essential roles in intracellular transport, separation of the chromosomes during mitosis and meiosis, and cytoskeletal dynamics. The mutations and deficiencies of molecular motors can lead to disease, such as inherited neuropathies, severe myopathies and chronic infections of the respiratory tract. Therefore, the study of molecular motors provides a new strategy for the treatment of many diseases. In this article, the discovery, biological roles and application of molecular motors are comprehensively reviewed.