【Objective】This study is oriented to explore effects of salt-tolerant trees different in species ameliorating coastal saline-alkali soils for screening trees suitable for establishment of shelterbelts and ecological greening in coastal areas.【Method】Three different species of trees, i.e. Tamarix chinensis (salt-secreting arbor), Rhaphiolepis umbellata (salt-rejecting shrub), and Ulmus pumila (salt-rejecting arbor) were planted in a tract of mudflat of saline-alkali soil in the Songbu Polder on the coast of Wenzhou. Two years after the trees were established, soil samples were collected from the rhizospheres of the trees for analysis of particle size distribution of soil aggregates and key physicochemical properties of the aggregates by particle size, including soil organic carbon (SOC), dithionite-citrate-bicarbonate-extractable Fe (hydro)oxides (DCB-Fe), total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and readily available potassium (AK).【Result】Compared with the soil in the bare-land (CK), the soil in the rhizosphere of T. chinensis, R. umbellata, and U. pumila was 0.14, 0.43 and 0.39 lower in pH and 80%, 70% and 72% lower in electrical conductivity (EC), respectively. The soil particle size of CK was <0.053 mm, while soil aggregates were formed in the rhizosphere of the trees with the content of soil micro-aggregates (0.25-0.053 mm) being 5.0%-5.9%, and the content of macro-aggregates (2-0.25 mm) being much lower, accounting for less than 1% of the total of soil aggregates. The content of SOC increased significantly in the rhizosphere soils, but the content of DCB-Fe decreased significantly (P<0.05), especially in micro-aggregates, which suggests that soil aggregation was coupled with Fe removal and C accumulation. Soil nutrients, including TN, AN and AP were elevated in content within the rhizospheres of all three species. The content of TN (1.20 g·kg^-1) and AN (42.6 mg·kg^-1) in the rhizosphere soil of U. pumila was 15.4% and 23.8%, respectively, higher than those in CK. The content of AN (85.8 mg·kg^-1) in micro-aggregates was the highest among the aggregate fractions in the rhizosphere of U. pumila . Interestingly, much higher AP contents in silt-clay aggregates (16.4-19.0 mg·kg^-1) than those in micro-aggregates (10.4-11.4 mg·kg^-1) were detected in the T. chinensis and R. umbellata plantations, whereas no difference was observed in U. pumila rhizosphere soil (P>0.05). After establishment of the trees, AK decreased significantly or by 4.5%-11.5% in rhizosphere soils as compared that in CK (P<0.05). For all the rhizosphere soils, the content of AK varied in the range of 115.0-216.3 mg·kg^-1 in micro-aggregates, which was significantly lower than those in silt-clay aggregates (303.0-342.0 mg·kg^-1).【Conclusion】 Cultivations of the salt-tolerant trees can ameliorate saline-alkali soils by reducing salinity and improving soil structure and soil fertility. T. chinensis, R. umbellata, and U. pumila could all be used as effective pioneer trees for mudflat reclamation projects. Among these species, U. pumila appeared to be the most effective thanks to its high capability of carbon and nitrogen enrichment in the rhizosphere soil.