In this study, the effects of different application positions of starter phosphate fertilizer on seedling growth, root morphological development and the spatial matching degree of soil phosphorus nutrients and root system of drip-irrigated maize were studied through the simulation experiment. The purpose of this study was to provide a theoretical basis for clarifying the best application position of starter phosphate fertilizer and its effect on maize seedling growth. Using root box, four starter phosphate fertilizer treatments were set up, which were (1) simulated drip application (T1), (2) starter fertilizer applied at 5 cm horizontally to seed and 5 cm below the seed, by hole application (T2), (3) starter fertilizer applied at 5 cm horizontally to seed and 12 cm below the seed, by hole application (T3) and (4) no starter fertilizer (CK). According to the field starter phosphate fertilizer application amount (P₂O₅ 30 kg/hm²), the amount of starter phosphate fertilizer was P₂O₅ 0.2 g/kg soil. The effects of different treatments on maize seedling growth, root morphological development, spatial matching degree of soil phosphorus nutrients and root, and evaluation of spatial matching degree of phosphorus nutrients between root and soil were analyzed. The results showed that at 14 and 21 days after maize emergence, the application of starter phosphate fertilizer significantly increased the total root length, total surface area, and the number of primary and secondary lateral roots. The overall performance was the highest in T2, followed by T1 and T3, and the lowest in CK. But there was no significant difference in the number of maize primary roots and main radicle root length among the treatments. At 21 days after maize emergence, the soil available phosphorus mainly distributed in the range of 0—9 cm vertically and 0—18 cm horizontally in T1, in the range of 3—12 cm vertically and 0—11 cm horizontally in T2 treatment, and in the range of 11—20 cm vertically and 0-11 cm horizontally in T3 treatment. The root was mainly concentrated in the 0—9 cm soil layer in T1, and in the soil layer of 5-15 cm vertically and 0-12 cm horizontally in T2 treatment, and in the soil layer of 12—18 cm vertically and 0—9 cm horizontally in T3 treatment. The spatial matching degree of root and soil phosphorus nutrient distribution was T2>T3>T1. At 7 days after maize emergence, there was no significant difference in the dry weight and phosphorus nutrient accumulation of maize among the four treatments. At 14 and 21 days after maize emergence, the dry weight and phosphorus nutrient accumulation of maize in the treatments with starter phosphorous fertilizer were significantly higher than those of CK, and the dry weight and phosphorus uptake of T2 were the highest and significantly higher than those of T1 and T3, but there was no significant difference between T1 and T3. Applying starter phosphate fertilizer at 5 cm below the seed showed the best effect on maize growth. The main reason was that phosphorus nutrient distribution was best fit the root distribution pattern in soil, this was benefit for root absorption of phosphorus. At the same time, it promoted the proliferation of maize lateral roots in fertilizer application area, expanded the contact area between the root and the soil, and increased the phosphorus absorption and biomass of maize. The application of starter fertilizer by drip irrigation could also promote root growth, however, the root distribution was shallow.