The invention relates to a method for preparing iron oxide particles having controllable morphology and size. The method comprises the following steps: 1, adding a surfactant into an organic solvent,fully stirring the surfactant and the organic solvent to obtain a uniformly dispersed suspension, adding an inorganic alkali and a soluble iron salt into the suspension, and fully stirring the inorganic alkali, the soluble iron salt and the suspension until the inorganic alkali and the soluble iron salt are completely dissolved; 2, pouring a solution prepared in step 1 into a closed heating container, and carrying out a thermal reaction; and 3, separating a precipitate in the obtained reaction solution through a centrifuging or magnet process, repeatedly washing the precipitate with ethanol and deionized water, and carrying out vacuum drying to obtain a black solid which is the final product. The accurate and highly-efficient regulation of the size and the morphology of nano-particles is realized through adjusting the proportion of the reaction solvent and the addition amount of the inorganic alkali under same reaction conditions, the size of the obtained particles is 20-400 nm, and solid particles, nano-clusters, triangular prisms, regular octahedrons and other various morphologies can be obtained. The preparation method has the advantages of simplicity, and green and environmentally-friendly raw materials and technology, the product has the advantages of high crystallinity, stable structure, uniform size and gram level reaching yield, and the preparation method is of great guidance significance to preparing magnetic nano-particles.