The invention relates to a preparation method of natural glue, and belongs to the technical field of glue preparation. The preparation method provided by the invention comprises the following steps: firstly, mashing drosera capillaries; performing alcohol extraction and filtration through ultrasonic waves; performing alkali extraction on filter residues; combining filtrates to obtain an extraction solution of drosera capillaries; adding hydrochloric acid to adjust pH, filtering, reducing pressure and distilling to obtain a sticky substance; performing ammonia extraction on aloe; fermenting an extraction solution to obtain a stock solution; mixing the stock solution with the extraction solution of drosera capillaries; finally, adding starch and the like to be mixed and stirred to prepare the natural nontoxic glue. The preparation method provided by the invention is simple in preparation process; the adopted raw materials are natural and environment-friendly; the prepared glue is high in adhesion strength, has no hardening delamination after bonding, can be used normally in high temperature environment, is fast to bond and convenient to apply, effectively improves the work efficiency, and is suitable for large-scale application.