The invention discloses a preparation method for a lithium iron phosphate positive electrode material with high rate, high capacity and excellent low-temperature performance by a reverse salting out method. The preparation method aims to synthesize a lithium iron phosphate material by a novel method which is relatively easy to implement, and the electrical conductivity of the material is improved.The preparation method comprises the steps of (1) performing high-pressure permeation; (2) performing salting out and crystallization in a circulation way; (3) tabletting and shaping; and (4) performing high-temperature sintering to form a three-dimensional structure, in which heat preservation is performed on a material of the step (3) for 4-12 hours at 600-800 DEG C, nitrogen is needed to be introduced during the whole sintering process, and the pressure is maintained at 0.1-1MPa. The preparation method has the advantages that a few amount of raw materials for synthesis are used, the process is simple and is easy to operate, the electrical conductivity of the synthesized lithium iron phosphate material reaches 10<-2>s/cm under the condition that other additives are not added, the specific area is small and can reach 10m<2>/g, half-cell test shows that the discharging capacity retention rate is 90.9% after circulation for 1,000 periods at 1C, the initial discharging specific capacityis 200.0mAh/g at 0.2C, and the capacity is 125mAh/g or above at 5C.