Abstract: By combining the merits of the line commutation converter based HVDC（LCC-HVDC）and the voltage source converter based HVDC（VSC-HVDC）,we have the hybrid high-voltage direct current（HVDC）transmission system that is a new topology of HVDC.A comprehensive technical analysis is made of hybrid-HVDC including the main circuit design,converter topology,control and protection system,to point out the technical barriers and future development directions.An overview of the application and status quo of hybrid-HVDC projects across the world is also given.With an eye to China’s energy development strategy,characteristics and demands of future grid advancement,the research and engineering application trend of hybrid-HVDC projects is demonstrated,which shows that the hybrid-HVDC technology has a critical role to play in the future grid arena.