Abstract: With the rapid development of wind power, large-scale wind power transmission is gradually becoming the main way of wind power usage and improvement of wind power availability. Large-scale wind power transmission includes transmitting through series compensation and HVDC. These two transmission both have the risk of sub-synchronous oscillation. The characteristics of three typical wind turbines is stated. The generating mechanism, characteristics and suppression measures of sub-synchronous oscillation in two transmission systems are generalized. The analysis method appropriate for sub-synchronous oscillation in large-scale wind power transmission is summarized. At last, the research prospect on this field is explored.