Abstract: Sweet sorghum, a raw material for renewable bioethanol production by utilizing its juice, has been of global interest as an essential alternative and clean bioenergy crop for fossil resources and has excellent potential for the phytoremediation of arid saline lands because of its high biomass and adaptation to harsh environments. With the objectives of increasing sugar prodcution, lowering input, and improving soil, a two-year field experiment was conducted in the saline soils of the Yellow River Delta, where the soil is rich in potassium (K) but deficient in phosphorus (P). The parameters of brix value and nutrient content in each internode (IN) of the whole stalk, biomass, and soil properties were analyzed. The results showed that the peak sugar content of sweet sorghum was located in the middle INs but decreased at both the lower and upper INs along with the normal distribution; therefore, the middle INs had a higher brix value that should be prioritized. The combined application of K and P, rather than P alone, as topdressing promoted brix value and contents of N and P in the INs. The application of P as either basal or topdressing fertilizer had no positive effect on brix value, despite the soil being deficient in phosphorus. In contrast, application of P combined with manure stimulated sugar accumulation rapidly as sweet sorghum approached maturity, improved Na content in INs, inhibited Na transfer to grains, shortened internode length, increased both the content of SOM and Ca in the 0–60 cm soil layer, and decreased the pH of the 0–30 cm soil layer. Fertilization rates per hectare were recommended as follows: 80–120 kg P₂O₅ combined with 213 kg organic matter, together with 90 kg N as basal, 52 kg K₂O as topdressing during the jointing stage. In addition, the stalks can be cut at 138 d after seeding to obtain higher sugar and nutrient content, improve soil fertility, and reduce salinity. The above results provide a basis for the subsequent planting of sweet sorghum in saline soil. This important bioenergy crop will significantly facilitate the development of phytoremediation for both phosphorus-deficient and potassium-rich saline soils.