The invention relates to a novel method for preparing molecularly imprinted polymer without functional monomer or crosslinking agent. The method comprises the following steps: sufficiently mixing a camellia seed shell powder raw material, phloroglucinol auxiliary and a template molecule in water, and transferring into a stainless steel reaction kettle; and carrying out a low-temperature hydrothermal reaction to generate carbon microspheres, and forming irregular cavity imprinting in the microspheres. The preparation method is precise in process, is simple and feasible, and is an ideal method for preparing the molecularly imprinted polymer; and the product has low content of impurities and nice appearance, is spherical particles with regular and slightly rough surface, and has a grain sizeof about 1.5mu m. The preparation process does not need toxic organic solvent or expensive functional monomer or coupling agent; and the prepared imprinted polymer has uniform grain size, high biocompatibility and environment friendliness, and can be expected to be widely applied to the fields of biology, pharmacy and the like.