The invention relates to a preparation method for preparing a SnO2 nanorod cluster by using a one-step hydrothermal method. The method comprises the following steps: respectively dissolving a stannum source and an alkali in deionized water, dissolving a crystal growth guide agent in a mixed solution of deionized water and ethanol, uniformly mixing the stannum solution and alkali solution, dripping the crystal growth guide agent for stirring so as to form Sn(OH)62-sol; carrying out a hydrothermal reaction at the temperature of 120-260 DEG C, so that the crystal center grows according to a certain crystal orientation; and naturally cooling to room temperature after the reaction is ended, filtering, washing, drying, thereby obtaining the product. The hydrothermal synthesis method disclosed by the invention is low in equipment requirement, easy to operate and easy for large-scale production. The various used solvents are environmentally friendly, and toxic substances are not produced; and the prepared SnO2 nanorod cluster has the properties of large specific surface area and high orientation and has wide application prospects in the aspects of catalyst carriers, gas detection, field emission microelectronic devices and lithium ion battery electrodes.