Offshore wind power has become an important development direction in the world and the number of offshore wind farms is increasing. With the continuous use of offshore wind turbines, offshore operators need to maintain wind turbines on a regular basis. Due to the influence of wind, wave, current and tide, the difficulty and risk of offshore access and landing are increased. In offshore operations, access systems are often used to transfer people and equipment. In order to make offshore transfer operations safer and more reliable, many types of maritime access systems have been built to provide the best possible compensation for movements caused by wind and waves. This paper mainly introduces the different types of access gangway system with different motion compensation techniques, crane systems for offshore access and hydraulic clamping system on ships. In addition, the access methods built on the wind platform is also reviewed. Based on the technical analysis on the primary offshore access methods, three-level compensation is suggested for the domestic offshore access system on operation and maintenance ships, especially for application of wind farm further from shore in the future.