The invention relates to the technical field of agricultural planting, and particularly discloses a plant fermentation extract for improving soybean planting soil and a preparation method of the plantfermentation extract. The plant fermentation extract for improving the soybean planting soil is characterized by being prepared by taking cape jasmine, tricholoma matsutake, dried lumbricus, hirudin,cordyceps sinensis, pollen, radix sophorae flavescentis, liquorice, hippophae rhamnoides, Chinese wolfberry, pericarpium citri reticulatae, salicornia europaea, cyrtomium fortunei, radix stemonae, akebiaquinata, iron-enriched yeast, selenium yeast, oyster, magnesium yeast and soybean germ as raw materials. Those raw materials are mixed according to certain weight proportion. The plant fermentation extract is made through fermention, extraction, and flour milling process. Raw materials are easy to obtain, the preparation process is simple, the soil structure is effectively improved, the numberand activity of effective microorganisms in soil are increased, the soil enzyme content is increased, soybean growth, yield increase and quality improvement are facilitated, and the method is suitable for wide application and popularization.