A preparation method of a planting fertilizer used for garden landscape trees comprises the following steps that firstly, chernozem, sedumviviparum, waste tobacco leaves, peat soil, affine cudweed, spiral seaweed and biotechnology fulvic acid are mixed, mashed, placed in a fermentation pool and mixed with water for stirring, and a mixture is obtained; secondly, carbendazim and a microbial strain agent are added into the mixture, seal fermentation is conducted, and a fermented material is obtained; thirdly, urea, calcium superphosphate, diammonium phosphate, potassium sulfate, magnesium sulfate, ferrous sulfate and a Chinese medicine residue extracting solution are added into the fermented material and then placed in a mixing device for mixing and stirring, and a stirred material is obtained; fourthly, vermiculite, plant ash and sawdust are mixed and then added into the stirred material for mixing, and a semi-finished product is obtained; fifthly, the semi-finished product is dried, cooled, screened and bagged, and then the finished product can be obtained. By means of the planting fertilizer, the growth of plants can be promoted, the plants are protected from being infracted by harmful bacteria, the fertility of soil is effectively improved, and the planting fertilizer is suitable for being applied on the garden landscape trees.