The invention discloses a peak modulation control method of a large-scale wind-light-power ultrahigh-voltage DC sending-end system in the field of peak modulation of a sending-end power system. The peak modulation control method comprises the steps of building a sending-end system peak modulation target function considering trans-region DC peak modulation; building a constraint condition of powergeneration-load power balance, wind-light machine set output fluctuation, trans-region DC peak modulation, hydrothermal power machine set peak modulation, sending-end system power transmission; and calculating to determine day-ahead output power plan of DC transmission power, wind-light machine set output and hydrothermal power machine set output, and outputting a plan curve. According to the peakmodulation control method of a large-scale wind-light-power ultrahigh-voltage DC sending-end system, provided by the invention, the characteristic of DC power transmission adjustment flexibility canbe fully developed, the DC transmission plan is flexibly adjusted, the DC plan is used for bearing a part of peak modulation task, new energy absorption can be effectively promoted, and the peak modulation standby demand of a power grid also can be reduced.