Disclosed is a filter-pressing method for a belt-type sludge filter press. The filter-pressing method for the belt-type sludge filter press comprises the steps of flocked sludge treatment, self-gravity dehydration treatment, pre-pressing dehydration treatment and high-pressure dehydration treatment, wherein the step of high-pressure dehydration treatment comprises a line contact filter-pressing step which is completed though a first filter-pressing roller; the first filter-pressing roller is in a hollow spline type and is composed of a plurality of hollow and spaced round reinforcing bars. When entering a pressure area, materials can move forwards along a filter belt in the pressure area and pressure increases continuously, the size of the materials can be reduced under pressure, free water contained in the materials can reach a saturated state, and under line contact pressing, the dehydrating speed can be increased by 3-4 times.