The invention provides a cable duct firewall. The cable duct firewall is manufactured from a fireproof material, and has a fireproof function; meanwhile, cable standby holes are formed in the cable duct firewall so as to facilitate later dilatation or exchange maintenance, and the cable duct firewall is not need to be dismantled; a water-flowing flood prevention tank is formed in the cable duct firewall so as to facilitate water-flowing flood prevention and washing maintenance in a cable duct; moreover, a baffle plate of the cable duct firewall is manufactured from fireproof plates capable of preventing corrosion and water, so that corrosion of the fireproof plates is avoided; a transparent upper cover of the cable duct firewall is transparent, the upper surface is antiskid, the lower surface is anti-fog and fireproof, and the bearing pressure is greater than a preset pressure value, so that potential safety hazards in the prior art are avoided.