The invention discloses a direct-current
submarine cable which comprises a conductor layer, an optical cable layer, a first circulating cooling layer, a second circulating cooling layer, a shielding layer and a protective layer. The cross section of each layer is a concentric circle, and the optical cable layer, the first circulating cooling layer, the conductor layer, the second circulating cooling layer, the shielding layer and the
protection layer are sequentially distributed on the direct-current
submarine cable from inside to outside. The optical cable layer is arranged in the conductor layer, so that the monitoring unit is closer to the conductor layer, timely early warning is facilitated when an abnormal condition occurs, and a fault point is accurately positioned. After the optical cable layer is built in, a filling layer for protecting the optical cable layer can be removed, the overall outer
diameter of the
submarine cable is reduced, and laying is facilitated. Circulating cooling
layers are respectively arranged between the optical cable layer and the conductor layer and between the conductor layer and the shielding layer, so that the actual
operation temperature of the direct-current
submarine cable is reduced, and the output capacity is improved.