The invention discloses an anti-flaming antibacterial agent. The anti-flaming antibacterial agent is a water solution of chitosan and phosphorus-containing inorganic acid and is obtained by mixing thechitosan and phosphorus-containing inorganic acid, the stability is good, the broad spectrum antibacterial performance is achieved, phosphorus-containing acid is adopted as an acid source, chitosan is adopted as a carbon source and an air source, and therefore the outstanding anti-flaming performance is achieved. Meanwhile, the invention discloses a preparation method of the chitosan solution with the anti-flaming and antibacterial performance, raw materials of the preparation method are cheap and easy to obtain, no organic solvent or formaldehyde or other toxic or harmful reagents is adopted, the preparation process is simple, conditions are mild, no by-product is generated, the method is rapid, saves energy and generates no contamination, and the agent can be industrially produced in large scale. The chitosan solution with the anti-flaming antibacterial performance is wide in application range and is used for arranging cotton, polyester, polyester cotton and other textiles, the textiles have the broad spectrum antibacterial property and good anti-flaming performance, and the application prospect is achieved in the fields of public transport, home decorations, biological medicineand the like.