The invention relates to a preparation method for nanocluster structure iron phosphate, which comprises the following steps of: 1) adding ferric salt solution and inorganic phosphorous compound into a percussion flow device to be mixed, or adding ferrous salt solution and inorganic phosphorous compound into the percussion flow device, meanwhile, adding oxidant into ferrous salt solution, mixing after the ferrous salt solution is completely oxidized, and obtaining mixed solution containing ferric iron ions; and 2) keeping the stirring state, regulating and controlling a reaction system by alkaline solution at a certain reaction temperature, meanwhile controlling the percussion flow speed to be 1000-3000rmp, continuously stirring after the alkaline solution is added, ageing, separating, washing with pure water, and drying to obtain the nanocluster structure iron phosphate. The preparation method for the nanocluster structure iron phosphate has the beneficial effect of simple technical process, and the good-dispersibility nanocluster structure iron phosphate of which the primary particle diameter is 10-100nm and the secondary particle diameter is 1-3mu m can be obtained.