The invention discloses a power regulation method and system for a large-scale new energy access direct current power grid. The method comprises the following steps that: collecting a section active power value on a new energy power gathering position in real time; carrying out calculation to obtain a regulation key parameter, wherein the regulation key parameter comprises a threshold value interval formed by a regulation upper limit threshold value and a regulation lower limit threshold value; judging whether the section active power value exceeds the threshold value interval or not in real time; and if the section active power value exceeds the threshold value interval, according to a preset power regulation quantity value, sending a power regulation instruction to each sub-station to finish the section active power regulation. By use of the method and the system, when new energy power exceeds the rated capacity of a current converter, large power deficiency and disturbance caused bygenerator tripping or current converter locking can be avoided. By use of the method and the system, new energy output and the use ratio of the current converter can be improved, meanwhile, the section active power is dynamically regulated, the fluctuation ratio of the active power is lowered on a premise that the current converter guarantees to be safe, and the operation safety of the direct current power grid is improved.