The invention discloses a DC power real-time liftable capability calculation method and belongs to the electric power system and automation technology field. According to the method, based on the present DC operation conditions, overload capability determined by DC itself characteristics and section bearing capability of an AC power grid sending end and receiving end of an AC power grid are comprehensively considered, including power flow dispersion capability, transient stabilization capability and real-time power maximum transmission capability limited by AC voltage supporting capability and a present trigger angle value at a rectification side, and DC power real-time liftable capability can be determined. The method is advantaged in that an effective controlled variable is provided for realizing power emergency support, the DC modulation function is guaranteed to be effectively performed, a power unbalance problem of a power grid is alleviated, and power grid safety stability is improved.