Based on the soft soil characteristics of the Suzhou River in Shanghai,the saturated clay with fly ash and cement as solidified materials was used to research the effect of fly ash on the mechanical characteristics of cement soil.Through unconfined compressive strength tests under different cement dosage,fly ash and curing time,the mixing soil strength properties and deformation characteristics were investigated and a prediction method for the relation between unconfined compressive strength and curing period was proposed through the data fitting by using the Matlab.The results show that the stress-strain relationship of the stabilized soil will be changed from the plastic collapse intobrittle failure with the increase of fly ash and the age.When the fly ash dosage is too high,the coupling reaction is likely to occur,which affects the solidified effect.The best content ratio of cement to fly ash is 1:1,and the optimum amount of fly ash is from 14% to 18%.