Abstract: Along with the increasing demand for energy transition and rapid development of renewable energy, the energy structure and the power system structure are under reform in China. In order to adapt to the requirement of large-scale renewable energy transmission and construct a novel power system with renewable energy as the main body, research and application of flexible transmission technologies are in urgent demand. The significance of high voltage direct current（HVDC） technology based on power electronic equipment is getting more and more prominent. At present, practical HVDC technologies in China include line commutated converter based HVDC（LCC-HVDC） technology, voltage source converter based HVDC（VSC-HVDC） technology and hybrid HVDC technology. Based on the development and engineering practice of HVDC technologies in China, the key problems of HVDC transmission technologies for large-scale renewable energy in engineering application are summarized, and several technology directions are discussed, which provide reference for the development of renewable energy transmission technology.