In order to find out the effects of biochar on saltaffected soil physical-chemical properties and alfalfa growth in the Yellow River Delta, a pot experiment was conducted. Soil nutrients, soil structure, soil salinity, alfalfa yield and quality were analyzed under different biochar application levels (0, 0.5%, 1%, 2%, 5% and 10%). Based on grey correlation method, the biochar application effect was evaluated. The results showed that after biochar additions, soil organic matter and total nitrogen content were increased by 16.27%~246.65% and 6.38%~58.51%, respectively, but the changes of total phosphorus, available phosphorus and total potassium contents were relatively small. Meanwhile, soil bulk density was decreased significantly, while aggregates more than 0.25mm and soil aggregates stability enhanced under lower biochar rate. Compared with CK, biochar addition treatment reduced soil watersoluble salt contents by 38.90%~46.17%, and the contents of Mg2+, Cl-, and SO2-4 had significant reductions. The alfalfa yield was increased by 8.19%~43.00%, however, there was no significant difference in quality. With the increase of biochar application, soil fertility appeared a increasing trend, while aggregate stability showed an opposite character. Soil salt content and alfalfa yield were decreased first and then increased. Overall, biochar application improved the saltaffected soil physical-chemical properties and alfalfa growth. And 0.5% biochar addition rate had the best application effect.