Based on the soft soil foundation treatment project of the multi-purpose transfer area in the second harbor basin of Xuwei Port in Lianyungang，we carry out the solidification，dry-wet and freeze-thaw cycle tests of marine soft soil，and study solidification characteristics and strength deterioration mechanism of the marine soft soil solidified by cement together with lime，fly ash and gypsum.The results show that the cement mixed lime has the best solidification effect and durability，followed by cement mixed fly ash，cement mixed gypsum.The unconfined compression strengths of marine soil solidified by cement and lime are about 2.3 to 2.9 times and 4.7 to 7.8 times respectively of soil solidified by cement together with fly ash and gypsum.When the solidified soil subjected to one and five dry-wet cycles，reductions in the strength of solidified soils are 25.0% to 51.7% and 37% to 59.5% respectively.It means that the first dry-wet cycle has the most significant effects on the strength of solidified soil.After five freeze-thaw cycles，reductions in the dynamic elastic modulus and mass of the solidified soil decrease are 56.3% to 60.3% and 10.9% to 14.0% respectively.Dry-wet and freeze-thaw cycles induced strength reduction or even failure of solidified soil is mainly due to damage of microstructure and increase of soil voids.