Lightweight protective submarine cable

The invention discloses a lightweight protective submarine cable comprising an optical fiber unit, inner armor layers, a conductor, an insulating layer, an outer armor layer, and an outer sheath layer. The multiple inner armor layers are spirally twisted outside the optical fiber unit. The conductor is arranged outside the inner armor layers. The insulating layer is arranged outside the conductor through extrusion. The outer armor layer longitudinally wraps the insulating layer. The outer sheath layer is arranged outside the outer armor layer through extrusion. The optical fiber unit is composed of optical fibers and a stainless steel pipe. According to the lightweight protective submarine cable of the invention, the outer armor layer, which forms protection through longitudinal wrapping of a steel-plastic, aluminum-plastic or other metal/plastic composite tape material, is economic and applicable, and can better protect submarine cables laid in 1000m deep water and prevent submarine cable line breakage or in