The utility model discloses a buried power cable for a power grid. A central wire core, a first insulating layer, a fixed insulating layer, a fan-shaped filling layer, a triangular wire core unit andan outer insulating layer are arranged; the fan-shaped filling layers and the triangular wire core units can improve the anti-pressure capability; under the condition of very high pressure, the pressure is reduced; cavities are formed between every two adjacent fan-shaped filling layers at equal intervals. A plurality of sealing strips are arranged in the cavity at equal intervals; the cavity is divided into a plurality of sealed small cavity units by the plurality of sealing strips; the small cavity units are filled with a certain proportion of air; the air volume accounts for 1/10-1/2 of thevolume of the small cavity unit; the fan-shaped filling layers can extend towards the cavities at the two ends under negative pressure and relatively high pressure, so that a buffering effect is achieved, the triangular wire core units cannot cause mutual friction damage between two adjacent second wire cores, damage caused by exposed contact of the second wire cores is avoided, and the cable issafe and reliable.