In order to develop a new method for improving the aggregate structure of sandy soil, an indoor cultivation experiment was conducted to study the improvement effects of two polymer materials (PM) of poly γ-glutamic acid (PGA) and chitosan oligosaccharide (CO) combined with wood vinegar (WV) on the soil aggregates and enzyme activities of coastal saline soil. The results showed that, 1) The application of PM combined with WV significantly reduced soil pH and EC, and had varying degrees of promotion on soil organic matter. 2) The combination of 0.2% or 0.4% (soil mass percentage, the same below) CO and WV significantly increased the content of >0.25 mm macroaggregates and promoted the increase of mean weight diameter (MWD), while the combination of 0.4% PGA and WV significantly increased the content of 0.053-0.25 mm microaggregates and reduced the content of <0.053 mm clay particles. 3) The activities of soil catalase, urease, phosphatase, and sucrase increased by 4.07%-25.80%, 68.24%-189.76%, 0.46%-47.56% and 84.86%-350.16%, respectively, compared to the control under the condition of PM combined with WV. In conclusion, the combination of PM and WV could promote the formation of saline soil aggregates, improve soil aggregate structure, enhance soil aggregate stability and soil enzyme activity. This study has important theoretical and practical application values for the improvement of saline soil structure and the enhancement of soil fertility.