The invention discloses a preparation method of a spiral-like-shaped silver nanometer chain conductor bridging modified lithium iron phosphate composite material. The method comprises the steps of taking phosphoric acid, ferrous sulfate heptahydrate and lithium hydroxide as a phosphorus source, an iron source and a lithium source respectively, taking ascorbic acid as a reducing agent and a carbon source, taking oxidized graphene as an assembling platform, performing a hydrothermal method to synthesize a graphene modified rod-like composite material LiFePO<4>/RGO, next, dropwise adding an ammonium hydroxide solution to a silver nitrate solution, adding the obtained silver-ammonia solution and CH<3>CHO into a LiFePO<4>/RGO precursor suspension liquid, under water bath heating, reducing the silver-ammonia solution under existence of acetaldehyde, gradually self-assembling into a spiral-like-shaped silver nanometer chain, and finally manufacturing the spiral-like-shaped silver nanometer chain bridging modified lithium iron phosphate composite material LiFePO<4>/RGO/Ag-HNCs. The preparation method is simple in process and wide in raw material resource, and large-scale industrial production can be facilitated; and meanwhile, the prepared positive electrode material of a lithium ion battery is excellent in electrochemical performance and rate charge-discharge performance, long in cycling use life and wide in application prospect.