Abstract: Solidification technology plays a very important role for reuse of dredging. The organic matter in the silt remarkably influences the effect of solidification. In order to assess this, an experimental program of organic solidification was undertaken, the mechanical impact of the organic matter on the solidification was evaluated, the result showed that sodium leads to the organic matter's dissolution, which would weakened the solidification effect of the soil,and the fly ash could undermines the hindering effect of organic matter on the cement hydration, it effectly enhanced the strength of the soil, at last, a new composite additive was proposed, when treated with this, the short-term and longt-terrn strength was greatly increased, the fly ash provided large amount calcium ion the late growth rate was continuously increasing with the increase of the fly ash.