A rated voltage of 35kv or below shallow sea wind farm photoelectrical transmission composite cable comprises a cable core provided with a lead and a water-blocking filling piece, a water-blocking belting layer, a plastic-aluminum composite band layer, an internal sheath, a wire armoring layer and an external sheath, wherein the cable core are externally coated with the water-blocking belting layer, the plastic-aluminum composite band layer, the internal sheath, the wire armoring layer and the external sheath in turn, the cable core is internally provided with a fiber optic communication unit, a steel-tape armoring layer is arranged between the external sheath and the wire armoring layer. The structure of the fiber optic communication unit is as follows: a fiber loose tube is externally coated with an internal sheathing layer, an armoring layer and an external sheathing layer in turn. A conductor of the lead adopts two-tier structure: a central layer conductor is formed by twisting multiple stranded brass wires coated with water-blocking balm, and then coats a central layer semiconductive water-blocking band layer; an external layer conductor is coated outside the central layer semiconductive water-blocking band layer by multiple stranded brass wires coated with water-blocking balm, and then coats an external layer semiconductive water-blocking band layer. The invention has the complex function of optical communication and power transmission, one cable has two uses, thereby saving cost and facilitating laying; in addition, the cable has high strength, excellent wear resistance, corrosion resistance and waterproof function, and can adapt to the requirement for subsea use in long term.