Abstract: 【Objective】 To study the effects of magnesium fertilizer application times and distribution ratio on the yield and quality of processed tomatoes under calcareous soil conditions and screen the suitable magnesium fertilizer application scheme. 【Methods】 The field experiment was carried out with Jinfan 3166 and magnesium sulfate as experimental materials, and four treatments were set up: (1) 3 times of fertilization + front weight (50% magnesium sulfate was applied at seedling stage, DS3O); (2) 3 times of fertilization + post weight (50% magnesium sulfate was applied at the swelling stage, DS3E); (3) 6 times of fertilization + front weight (DS6O); (4) 6 times of fertilization + post weight (DS6E). 【Results】 The stem diameter, chlorophyll content and dry matter accumulation of processed tomatoes were significantly increased by increasing the number of times of magnesium fertilizer drip application (6 times) and the high proportion of magnesium fertilizer application in the later stage ("post weight "). At the same time, the greater the dosage of magnesium fertilizer (the larger the distribution ratio of magnesium fertilizer), the higher the nitrogen and magnesium content in the processed tomato fruit and the lower the calcium content. The yield and quality of processed tomatoes were significantly increased when the times of magnesium fertilizer drip application and the proportion of magnesium fertilizer late application were high ("post weight ") 【Conclusion】 The highest yield and the best quality of processed tomatoes are obtained when the amount of magnesium sulfate is 450 kg/hm², 6 times of drip application and the distribution ratio is post-weight(DS6E).