The invention discloses a red phosphorus-containing cable insulation layer which is prepared from the following components: basic resin, red phosphorus, ammonium polyphosphate, organic montmorillonite, an antioxidant and a modifier, wherein the basic resin is prepared from an ethylene-ethylene vinlacetate copolymer, a hydrogenated styrene-butadiene segmented copolymer and polyethylene; the antioxidant is 4,4'-sulfo-dis(6-tertiary butyl-3-methylphenol); and the modifier is pentaerythritol. The cable insulation layer disclosed by the invention does not contain halogen and is excellent in flame retardant effect.