【Objective】In the coastal areas of North Jiangsu exist enormous tracts of mudflat, which are important land reserves for exploitation in China. However, the existence of high soil salinity in the mudflat, once turned into farmland, not only reduces soil phosphorus availability, but also seriously restrains productivity of the farmland and phosphorus utilization efficiency. Biochar, humic acid and gypsum are considered to have good effects in ameliorating and utilizing the soil. Therefore, the objective of this study is to investigate effects of the use of these soil amendments on soil salinity-alkalinity and crop uptake and utilization of phosphorous in the soil.【Method】 For that end, a field microplot experiment was carried out in the fields of light saline soil (D) and moderate saline soil (Z), and an indoor pot experiment using the soils from the two fields. The experiments were designed to have five treatments for each of the two soils and three replicates for each treatment. The five treatments included (1) application of N only (CK); (2) conventional fertilizer (P); (3) conventional fertilizer + biochar (PC); (4) conventional fertilizer + humic acid (PH); (5) conventional fertilizer + gypsum (PG). The experiment initiated in 2017 under a crop rotation system of Barley-maize. Soil samples were collected from the 0~20 cm and 20~40 cm soil layers of each treatment once at each crop growing stage for analysis of effects of the amendments on soil salt content, soil pH and soil sodium adsorption ratio (SAR) and phosphorus absorption. 【Result】Results show that soil salt content in the coastal area of Jiangsu varied with the season markedly, that is, salt accumulating in spring, salt leaching in summer, soil uprising in autumn and salt stabilizing in winter. The soil salt controlling effects of the management measures were more significant in the 0~20 cm soil layer than in the 20~40 cm soil layer, especially Treatment PG. Treatment PG reduced the salt content in the 0~20 cm soil layer by 31.06% and 40.60% and soil pH by 0.67 and 0.51 in the soils light and moderate in soil salinity, respectively. Compared with CK, all the amendment treatments were lower in SAR and Na⁺ content in the 0~20 cm soil layer, which indicates obvious improvement in soil structure. In terms of decrease in SAR, treatments displayed an order of PG > PH > PC with the soil light in salinity and an order of PG > PC > PH with the soil moderate in salinity. All the amendment treatments promoted P uptake and yield of barley and maize in the soil light in salinity, while only Treatments PC and PG did in the soil moderate in salinity. After two rounds of rotation, in the soil light in salinity, Treatments PC, PH and PG were found to have increased the cumulative phosphate utilization rate by 4.9 times, 3.5 times and 1.8 times that of CK, respectively, while in the soil moderate in salinity only Treatment PC and PG showed similar effects. 【Conclusion】The saline soil in the coastal area of North Jiangsu varied with the season in soil salt content. The amendment of biochar, humic acid or gypsum can effectively promote removal of soil salt and alkali, thus improving the soil structure. Among all the amendments tested, gypsum is the best in decreasing soil salt content, pH and sodium adsorption ratio. All the amendments significantly promote crop P uptake, and hence increase cumulative phosphorus utilization rate and crop yield in the soil light in salinity. Humic acid shows a better effect in the soil light in salinity than in the soil moderate in salinity.