To solve the problems of slow hydration rate and low early strength of dredged soil solidified by steel slag，cement and steel slag were combined to improve the early strength of solidified soil.The influence of water content on the properties of soil solidified by cement-steel slag composite was studied through stress-strain curve，unconfined compressive strength，and elastic modulus. It is found that the strength of composite solidified soil increases with the decrease of dredged soil moisture content，and the properties of 1.25 times of liquid limit-soil are closer to those of 1.5 times liquid limit-soil. Based on the dredged soil strength of 100 kPa，the mixed ratio of cement and steel slag with different moisture content satisfying the strength standard was studied experimentally，which has important reference significance for the practical application of cement and steel slag composite curing agent. The microscopic analysis suggested that the mechanism of cement-slag composite action is that the reaction of cement hydration and slag pozzolan produce hydrated calcium silicate and orthorhombic，which can fill the pores，bond the soil particles and enhance the bearing capacity of the soil skeleton.