The invention relates to a preparation method of a gadolinium oxide magnetic resonance imaging nano probe with good biocompatibility. The preparation method of the gadolinium oxide magnetic resonance imaging nano probe with good biocompatibility comprises the following steps: 1) in a breaker, dissolving biomacromolecules in water, and stirring until the biomacromolecules are completely dissolved; adding a Gd(NO3)3.6H2O aqueous solution into the biomacromolecule solution, uniformly stirring, adding a NaOH aqueous solution, then regulating pH to be 10, and continuously stirring for 1 hour at room temperature, so that a colourless liquid is obtained; 2) purifying the obtained impurity-containing gadolinium oxide nano probe, carrying out dialysis for 24 hours, and changing water every other 4 hours, so that the purified nano probe is obtained after dialysis is carried out; and 3) carrying out free-drying, so that a flocculent white solid product is obtained. The preparation method of the gadolinium oxide magnetic resonance imaging nano probe with good biocompatibility has the advantages of simplicity, simple preparation conditions, environment-friendly raw materials, good water solubility, high T1 relaxation rate and low potential biological toxicity, is convenient for large-scale production and has large development potential and great application value in the field of medical imaging.