Abstract: Addressing challenges related to the poor constructability and low water-to-land strength ratio of polyacrylamide (PAM) cement in underwater repair of hydraulic structures, this study introduces polyacrylate emulsion (PAE) at concentrations ranging from 5% to 25% of the cement mass. The research aims to evaluate the construction performance of modified cement-based materials using truncated cone circular molds, the penetration resistance method, cement loss measurement by weighing, and suspended matter content testing by turbidimeter. Mechanical properties of PAE-modified PAM cement were assessed at 3, 7, and 28 days under both water and land forming curing conditions. Additionally, the microscopic modification mechanism of PAE on PAM cement was analyzed using a scanning electron microscope (SEM). The results show that the incorporation of PAE can significantly improve the fluidity of the slurry and prolong the setting time, but the underwater anti-dispersion performance is weakened. The flexural strength and bond strength of cement paste are significantly improved, but the compressive strength is reduced. The interpenetrating network structure formed by polymer and cement, the filling of pore area by membrane and the winding of hydration products such as ettringite ( AFt ) are the reasons for the improvement of mechanical properties. The membrane structure of cement specimens cured on land is more compact and the mechanical properties are better.