The invention relates to the technical field of chemical industry, and particularly relates to a production method for preparing calcium hydrogen phosphate and by-producing a special fertilizer for cucurbit. According to the production method, the effective absorption amount of nitrogen, phosphorus and potassium elements is analyzed according to the fertilizer requirement of cucurbit, and element content is regulated and collocated in a production process course, so that a prepared compounded-form compound fertilizer can furthest meet the requirement of the cucurbit, excessively high cost caused due to improper element collocation in the production of the compound fertilizer is reduced, and environmental pollution caused by that the compound fertilizer is solidified by adding excessive elements to soil is further prevented; and a high-purity calcium hydrogen phosphate product can be produced in the preparation process of the special fertilizer for the cucurbit by controlling the process condition of the production, so that the impurity removal cost needed when the calcium hydrogen phosphate product is prepared by adopting the traditional wet-process phosphoric acid method is made up, the purity of the calcium hydrogen phosphate product reaches more than 96%, the production cost is reduced, and outstanding economic benefit is achieved.