The invention belongs to the technical field of nanometer materials, relates to a method for manufacturing a lithium ion battery and discloses a method for preparing a carbon fiber modified positive pole lithium iron phosphate material for a lithium ion battery. The method comprises a freezing step of freezing cellulose; a mixing step of mixing the frozen cellulose with ferric phosphate and lithium carbonate; and a heating step of heating the mixed cellulose, ferric phosphate and lithium carbonate to obtain the lithium iron phosphate material for preparing a positive pole. The lithium iron phosphate material prepared by using the method, the battery positive pole made of the lithium iron phosphate material and the corresponding battery are further disclosed. The method for preparing the carbon fiber modified positive pole lithium iron phosphate material for the lithium ion battery has the advantages that the method for preparing the carbon fiber modified positive pole lithium iron phosphate material which can be used for the lithium ion battery and has good multiplying power and low-temperature performance is provided, and the method has high application value.