Five treatments were set up in a randomized block design for salinized maize fields in the Songnen Plain, Xianyu 335 maize was used as the test variety, conventional fertilization with nitrogen, phosphorus and potassium (CK), NPK reduction by 20% + biochar (CF1), N reduction by 20%+conventional phosphorus and potassium + biochar (CF2), phosphorus reduction by 20%+conventional NPK+biochar (CF3), and potassium reduction by 20% + conventional NPK+ biochar (CF4) were set to investigate the effects of nitrogen, phosphorus and potassium fertilizer reduction and biochar application on soil physicochemical properties and maize yield. The results showed that the CF4 treatment had a better improvement effect on soil properties, and its soil organic carbon (SOC), total nitrogen (TN) and effective phosphorus (AP) were increased by 13.40%, 5.93% and 58.86% compared with that of CK, the activities of sucrase (SUC) and alkaline phosphatase (ALP) were significantly increased. At the same time, the dosing treatment obviously promoted the accumulation of N, P and K in maize plants, the accumulation amounts of nitrogen, phosphorus and potassium increased by 3.32%-23.04%, 31.93%-38.65% and 5.51%-13.62% respectively compared with CK, indicating that the application of biochar can effectively promote the nutrient uptake by the plants. In conclusion, the combination of nitrogen, phosphorus and potassium fertilizer reduction and biochar can regulate soil nutrients, improve plant nutrient uptake, and increase corn yield, in which the treatment of 20% potassium reduction+conventional nitrogen and phosphorus + biochar has more potential for fertilizer saving and yield increase.