Cotton knitted flame retardant fabric has durable flame retardant property and can be washed for over 50 times. Such flame retardant fabric can effectively prevent flame spread and maintain their original performance at the same time. Flame retardant protective clothing made of such fabric have excellent laundering durability, soft texture, moisture adsorption, permeability, good flexibility, extensibility and producibility and is non-toxic, odorless and non-irritant. Knitted fabric is comfortable and close fitted, produces no tight sense and can fully reflect the body curve, so it can be used to make babies' and children's garments, pajamas, underwear, bedding and decorative cloth and also applicable to combat arms, such as pilots, marines, anti-explosion forces, vessel forces, artillery and armored forces working in special circumstances.