In order to figure out the effect of curing agent in sludge soil with the fly ash and lime as the main curing agent and TZ-01 as the additive, a series of experiments were conducted to study the strength characteristics of solidified soil and the influencing factors on the strength of solidified soil. Through experiments, the initial water content, organic matter content, main curing agent content, additive incorporation ratio, and age of solidified soil were analyzed. The results showed that the initial water content of the sludge soil hindered the growth of the solidified soil. The main curing agent and age growth can effectively enhance the strength of the solidified soil, and there was an optimum blending ratio of organic matter content and additive incorporation ratio. Based on the analysis of the stress-strain curve obtained from the unconstrained compression test of solidified soil, four stages of solidified soil under uniaxial compression were proposed. By processing and analyzing data, the water-cement ratio β was introduced, the effects of organic matter content, additive incorporation ratio and age were comprehensively considered, and the solidified soil strength prediction model was established.