Abstract: Dredging sludge has the characteristics of huge volume, high moisture content and low structural strength. Development of compound curing agent of sludge could efficiently solve its problem of space occupation and environmental pollution, promoting resource utilization of sludge. We selected cement as major curing agent, and carried out experiment on sludge solidified as subgrade filling. By experiment of single factor, this study implements the screen of main addition agents. We carried out further experiment to analyze the effect of addition proportion of curing agent to moisture content, unconfined compressive strength and CBR value of subgrade fillig. The results show that cement, flyash and offscum could improve the sludge strength efficiently, but flyash has a limited effect on reducing mosture content. In addition, heavy use of flyash would cause lamellar structure of solidified sludge. Systematically considering CBR value, puddlability and price, the compound curing agent is consist of 5% cement, 6% flyash, 50% offscum and 0.5% accelerator. The compound curing agent could improve the original sludge by forming skeleton structure and establishing hydrophobic channel.