The invention discloses a red phosphorus and fire-retarding polyamide composite and a preparation method thereof. The composite comprises the following components in percentage by mass: 30 to 97 percent of polyamide, 1 to 40 percent of red phosphorus, 1 to 60 percent of filler, 0.001 to 15 percent of corrosion stabilizer, 0.001 to 15 percent of precipitation stabilizer and 0 to 50 percent of other assistant. The total mass percentage of the components is 100 percent. The fire-retarding thermoplastic composition is prepared by mixing a specific stabilizer and other components and regulating the ratio of the components. The prepared fire-retarding thermoplastic composition can greatly reduce precipitation amount of phosphorus and improve stability, and therefore can ensure a material has high fire-retarding performance and mechanical strength. Formed products with small wall thickness are divided into a V-0 class and a V-1 class according to Underwriters Laboratories (UL)94 standards, and the phosphorus precipitation stability is improved. The fire-retarding thermoplastic composition may be sheets, plates or formed products, and is particularly applicable to electrical appliances and electronic parts. Concretely, the fire-retarding thermoplastic composition can be used to make lamps, such as lamp holders and plugs, connecting vessels, coil holders, capacitor cases or connectors, circuit breakers, relay shells and reflectors.