Due to serious soil salinization, the Yellow River Delta has become one of degraded ecosystems in China. Effects of different plantations, including Robinia pseudoacacia pure forest & mixed forest, on soil chemical properties were studied in order to explore the relationships between plantation modes and soil chemical properties and thus rationally utilize the land resources of large scale saline region. Results showed that creating R. pseudoacacia in coastal saline effectively inhibited soil salinization and degradation, reduced alkalinity, and improved soil fertility. The effect of soil alkali salt dischange of mixed plantation was better than that of pure forest. Soil chemical properties were significantly different under different plantation modes. Soil exchangeable calcium and magnesium did not show phenomenon of accunulation in sruface, but the effective sulfur and phosphorus did not change significantly. Moreover, there was a certain correlation between the chemical indicators. Soil pH value had significantly negative correlations with total nitrogen, exchangeable calcium and exchangeable magnesium and there was a significant negative correlation between soil available sulfur and available phosphorus. The integrated effect on soil properties in mixed plantation was higher than Robinia pseudoacacia pure forest. Moreover, the combined effects on soil fertility in different mixed modes were not the same. The mixed plantation of R. pseudoacacia and Fraxiinus velutina performed the best effects on soil fertility, followed by the modes of R. pseudoacacia×Ulmuspumila ＆R. pseudoacacia×Ailanthus.