The invention belongs to the energy transition material preparation technical field, in particular relate to a preparation method for lithium iron phosphate composite materials. The preparation method of the invention comprises the following steps: firstly, gulf red, phosphorus source, lithium source and carbon source are mixed in proportion; secondly, uniform ball milling is performed; thirdly, spray drying is performed; fourthly, high temperature heat treatment is performed under the protection of inoxidizing atmosphere, and then the lithium iron phosphate composite materials are obtained with an average grain diameter of 0.1 to 10 micrometers and a tap density of 1.2 to 1.5 gram per cubic centimeter. After the lithium iron phosphate composite materials are assembled into a battery, first discharge specific capacity of 0.2C multiplying power under room temperature can reach 150 to 160 mAh / g, and first discharge specific capacity of 1C multiplying power under room temperature can reach a high specific capacity of 140 to 150 mAh / g; after circulation for 100 times under various different multiplying powers, reversible capacity can still reach over 90 percent of the original capacity, thereby cyclicity is high. Moreover, safety is good, and the battery is environment friendly and has low cost, and can be widely applied in mobile telephones, notebook computers, various portable devices and the electric motor car field.