Abstract: In order to realize the comprehensive utilization of dredged sand in the lower Yangtze River and expand the source of fine aggregate, the effects of different maintenance temperatures on different dredged sand admixtures mortar characteristics were investigated. Using dredged sand as raw material, three mortar mix ratios with different dredged sand admixtures were designed, and the effects of four curing temperatures of 40, 60, 80 and 90℃ on the compressive and flexural strengths at different ages were investigated, The microstructures of specimens with different curing temperatures and different dredged sand admixtures were analyzed by combining X-ray diffraction, thermogravimetric-differential scanning calorimetry, scanning electron microscopy and mercury injection test. The results show that with the increase of curing temperature, the distribution of hydration products in mortar is uneven, which hinder the subsequent hydration reaction. The compressive and flexural strengths of mortar increase first and then decrease. The higher the curing temperature is, the greater the steam curing damage is. The particle size of dredged sand is very small, and it has good filling effect. Appropriate incorporation of dredged sand can improve the compactness of the system, and reduce the number of harmful holes and multiple harmful holes, thereby improving the mechanical properties of mortar. Under the condition of steam curing, the pore structure defects of mortar increase, and the optimization effect of dredged sand is amplified, which can offset some adverse effects of steam curing to a certain extent. The enhancement rate of the dredged sand on the compressive strength gradually decreases with the increase of the curing temperature, and the maximum could enhance 31.35%. The enhancement of the flexural strength increases first and then decreases, and the maximum could enhance 14.29%.