The physical and mechanical properties of soil are greatly influenced by temperature. Triaxial tests under different curing conditions were carried out on clay to investigate its thermomechanical behavior. This paper presents the findings of a laboratory investigation into the thermomechanical behavior of clay. Experimental results show that clay exhibits thermal consolidation properties. As temperature increases, the consolidation speed of clay accelerates, and the consolidation time shows a decreasing trend. Below the critical temperature, the stress-strain curve of the soil presents softening characteristics and brittle failure. Above the critical temperature, the stress-strain curve shows hardening characteristics and plastic failure. Clay exhibits a behavior similar to the “curing temperature” of concrete, where a longer curing time results in a greater principal stress difference. Within the critical temperature range, cohesion decreases with increasing temperature, while above the critical temperature, cohesion increases with temperature. Within the critical temperature range, the internal friction remains unaffected by temperature changes. However, above the critical temperature, the internal friction increases with temperature. The strength development of clay with curing time is divided into rapid growth, followed by a stage of less rapid growth and slow growth. The optimal curing time occurs during these rapid growth stages.