Abstract: Peanut has been one of the most important cash crops in recent years. This study aims to explore the effects of the tillage depths and planting densities on the photosynthetic behavior and peanut yield p in coastal saline-alkaline land. A split-zone experiment was conducted in a representative saline-alkaline land of the Yellow River Delta. Two time periods were divided into: 2023 and 2024, from May to September. The peanut variety “Yuhua 18” was used as the material. The influencing factor of the fracture zone was used to assess the peanut growth under different treatments. The influencing factor split-zone was adopted as the first major type of treatment area. Three treatments were set as the tillage depths of 10, 15, and 20 cm, respectively, noted as D1, D2, and D3, respectively. At the same time, the subzones were also divided, according to the different densities. Three treatments were taken as the planting density of 178 000, 212 000, and 261 000 plants per hectare, respectively, noted as R1, R2, and R3, respectively. Such partitioning was designed to explore the interactions of different tillage depths and planting densities under the planting mode for the precision sowing of the single grains. Together, a systematic investigation was made to determine the photosynthetic behaviors of peanut leaves at the critical reproductive periods, such as the seedling, flowering, pod setting, and pod filling stages. In addition, the components of peanut yield were also evaluated at the harvesting stage. The results revealed that there were significant differences in the peanut growth and yield potential under different treatments. Specifically, the chlorophyll content and net photosynthetic rate of peanut leaves were performed at the highest level under the combination of 212 000 plants per hectare and 20 cm tillage depth, indicating the maximum at the podding stage. The chlorophyll and photosynthetic capacity also increased the overall growth potential of the plant. The number of pods per plant and the rate of full pods were higher by 9.52% and 4.58, respectively (averaged for two years), compared with the rest treatments. The leaf area index of peanut leaves reached the maximum at the podding stage under the combination of 261 000 plants per hectare planting density and 15 cm tillage depth. An optimal combination of planting density and tillage depth was achieved to improve the plant population quality. Correspondingly, the kernel rate and pod yield were at least higher by 5.34% and 2.45%, respectively (averaged for two years), compared with the rest treatments. Therefore, two planting schemes were used as the preferred coupling mode of the high-yielding peanut in the coastal saline-alkaline land. The most suitable environmental parameters were determined for peanut growth, such as the appropriate water, air, and heat. The yield of peanuts was eventually improved due to the high efficiency of photosynthesis. The finding can also provide the theoretical reference for the high-yield peanut cultivation in the coastal saline-alkaline land. It is of great significance to explore the saline-alkaline land resources. Meanwhile, more planting modes can be suitable for the cropping patterns of the peanut in the saline-alkaline land, thereby expanding the cultivation area of peanuts. Furthermore, a stable supply of food and oil products can gain national security in the soil resources of saline-alkaline land.