Abstract: A pendulum-type landslide monitoring system includes an outer tube for being implanted into a ground to be monitored; a plurality of measuring units, vertically aligned inside the outer tube for independently measuring displacement at different depths in the ground; a guiding tube inside the outer tube for a flexible image capturing device to pass therethrough; and a water-level monitoring tube installed in the outer tube. Thereby, the flexible image capturing device can capture data of the displacement obtained by the measuring units, for an operator to identify displacement of a sliding surface in the ground, and to visually observe images of flowing groundwater captured by the flexible image capturing device in the outer tube, in order to further determining groundwater flow patterns as well stratums in the ground.