To improve the product quality of potassium dihydrogen phosphate, the potassium dihydrogen phosphate solution produced from a certain potassium dihydrogen phosphate unit is taken as the research object. By adjusting the pH of the solution (4.0-5.6) and combined with steps such as thermal settling, filtration, concentration, and crystallization, the effects of the pH of potassium dihydrogen phosphate solution on the total nutrient content, crystallization yield, impurity content, and crystal characteristics of the potassium dihydrogen phosphate product are experimented. The results show that with the increase of the pH of the potassium dihydrogen phosphate solution, the total nutrient content (mass fraction of KH₂PO₄) of the product gradually increases. When the pH reaches 4.80, the total nutrient content reaches a maximum of 98.07%, but the crystallization yield decreases significantly. At pH=4.45, the highest crystallization yield of 141.40 g is obtained, while the total nutrient content is at its minimum of 91.17%. Adjusting the pH to above 5.00 using potassium hydroxide solution is found to be effective in removing impurities such as calcium and magnesium ions from the solution, thereby reducing product impurities. Considering the balance between product quality and production efficiency, it is recommended that the pH of the potassium dihydrogen phosphate solution should be controlled between 4.80 and 5.00 in industrial production, so as to balance the contradiction between total nutrient content and crystallization yield, and to reduce impurity content.