DC access capability for multi-infeed HVDC power transmission system is an important issue which gets power companies concerned greatly. From the problems caused by large scale multi-infeed HVDC, the main limiting factors of DC access capability are analyzed and the current researches on DC and new energy access capability are summarized. Based on these the calculation method and the next research directions of DC access capability are discussed. DC access capability is a multi objective optimization problem, and the next key study is to build the system optimal model to evaluate the DC access capability of multi-infeed HVDC power transmission system. For the main limiting factors the suggestions to improve DC access capability and optimize the layout of multi-infeed HVDC are proposed.