Abstract: This study first investigates the effects of humic acid, and salt concentration on lime-stabilized Ariake clays with emphasis on their mechanical properties. The results show that the strength and the yield stress of lime-stabilized clay with high humic acid are low due to the obstruction of the pozzolanic reaction, and the effect of humic acid on strength of stabilized clays decreases with increasing salt concentration because the humic acid becomes inactive at higher salt concentration. Then through analyzing the microstructure feature of the stabilized clays, some relationship between microstructure and mechanical properties of lime-stabilized clays are established.