To improve the utilization rate of waste clay, a composite curing agent composed of cement, alkali excitation agent, siliceous solid waste material and sulfate solid waste material was used to cure a waste clay. Unconfined compressive strength test (UCS), water stability test, X-ray diffraction test and scanning electron microscope(SEM) test were carried out to capture the mechanical behavior and reinforcing mechanism of the solidified clay. The results show that there is a significant solidification effect on the clay when the dosage of curing agent is from 10% to 12%, and the water stability coefficient of solidified clay is larger than 80%. The UCS of the solidified clay with 12% curing agent content is 2.45 MPa after curing for 28 days, which is 2.33 times the UCS of the solidified clay at a curing time of 7 days (1.05 MPa). A large number of hydration products such as calcium silicate (aluminate) hydrate and ettringite produced in the solidified clay can improve the performance of solidified soil by improving the micro-pore structure of soil and strengthening the cementation between aggregates. The present research can provide reference for the resource utilization of waste clay.