The invention belongs to the field of inorganic nanometer materials and biosensors, and discloses a halloysite coating used for capturing tumour cells and a preparation method and application thereof. Specific halloysite nanometer structures are prepared on different substrates through a coating method, and target cell specific recognition molecules are fixed. Or a rough nanometer structure is directly used, the reinforced three-dimensional topology mutual function between the cell surface structure and the substrate rough nanometer structure is used, and more target cell recognition molecules can be fixed on the nanometer rough structure compared with a smooth surface. The flow speed of fluid in blood can be lowered based on the rough nanometer surface structure, and therefore the chance of interacting with cells is increased, the cell capturing efficiency of the halloysite nanometer structure is improved, and the 3h capturing rate for most tumour cells exceeds 80%. The method is easy to operate, low in energy consumption and high in preparation efficiency. In the whole preparation process of the substrates, no toxic and harmful substances are generated, and no pollution is caused to the environment.