Amelioration experiments of marine medium-saline soil by mixed cultivation of sesbania growing in waterlogged soils with fish culture(MCSWFC) was carried out in soils improved with single fish culture(SFC) previously,with cultivating sesbania in upland as a control.Results obtained were as follows:1.Sesbania plants grew much better in waterlogged soils with fish culture than in upland.The fresh weight of lateral roots,root nodules and seeds yield of sesbania growing in waterlogged soils was 10 times,15 times and 1.5 times of that in upland respectively.2.Efficiency of salt leaching in soil depth of 0-20 cm in the three treatments was as following order:MCSWFC>cultivating sesbania in upland(CSU) SFC,while it in soil depth of 0~100 cm was MCSWFC>SFC>CSU and there were same tendencies for SAR and Na⁺/Ca²⁺ ratio.3.Total soil nitrogen and alkali-hydrolyzable nitrogen in soil depth of 0-10 cm in MCSWFC was almost the sum of those in the treatments of CSU and SFC and it was also taste for soil organic carbon.And the increase rates of soil available phosphorus and slowly available phosphorus were MCSWFC>CSU>SFC.