The invention relates to the technical field of plant extraction and discloses a preparation method of a cyclocarya paliurus leaf extract. The preparation method comprises the following steps: extracting cyclocarya paliurus leaves by adopting a high-temperature water extraction method or a low-temperature refluence water extraction method, so as to obtain an extracting solution; removing precipitates from the extracting solution in a disc separation manner, concentrating supernatant, carrying out UHT sterilization and filtration, so as to obtain filtrate; carrying out freeze drying on the filtrate, and crushing and sieving dried material, so as to obtain the cyclocarya paliurus leaf extract. The high-temperature water extraction method or the low-temperature refluence water extraction method is combined with processes of disc separation, vacuum concentration or reverse osmosis concentration and freeze-drying for use, and meanwhile, parameter setting of each process stage is optimized,so that the yield of the cyclocarya paliurus leaf extract is remarkably increased, and furthermore, the cyclocarya paliurus leaf extract has relatively good fluidity, uniformity, moisture resistance and solubleness.