The invention discloses a preparation method for organic fertilizer for preventing and treating secondary salinization of a solar greenhouse vegetable field. The preparation method comprises the following steps: (1), mixing cow dung or a mixture of the cow dung with one or more of goat manure, chicken manure, pig manure, straws and waste tobacco shreds according to the volume ratio of 1:1 and fermenting, thereby obtaining a material A; (2), preparing earthworm cast after cow dung is fermented; (3), crushing crop straws, adding the crushed straws to chicken manure or pig manure, and enzyme microorganism, mixing uniformly, building stacks and fermenting, thereby obtaining a material D; (4), mixing the materials A, C and D to obtain a material E; (5), mixing the material E, calcium cyanamide, diammonium phosphate, zinc sulfate and sodium borate, thereby obtaining finished products organic fertilizer. According to the preparation method for the organic fertilizer for preventing and treating the secondary salinization of the solar greenhouse vegetable field, wastes of agriculture and animal husbandry industries are utilized as main materials and match natural antibacterial materials, such as lime nitrogen, in accompany with secondary and trace elements, such as calcium, boron and zinc, so as to solve problems of vegetable wilting and soil harmful bacteria caused by the salinization of the solar greenhouse vegetable field. Compared with application of common fertilizer, application of the prepared organic fertilizer has the advantages that the fertilization costs are reduced and the yield and quality of vegetables are improved.