A landform monitoring system includes a pressure sensing device mounted on a mounting frame, and including a housing unit configured with an accommodating space and having first and second openings in fluid communication with the accommodating space. A pressure sensor is attached to the housing unit, and seals the first opening. A flexible sheet is attached to the housing unit and seals the second opening. A fluid medium is filled fully in the accommodating space. When the sheet deforms as a result of an external pressure acting thereon, a pressure corresponding to the deformation of the sheet is transmitted to the pressure sensor via the fluid medium such that the pressure sensor generates a pressure sensing signal corresponding to the external pressure.