The invention relates to the technical field of slope support construction methods, and discloses a combined slope support construction method which comprises the following steps: 1) leveling treatment; 2) pouring and drilling to form a pile body; 3) constructing inter-pile plates which are longitudinally arranged, and fixedly arranging the inter-pile plates and the pile body; 4) forming a plurality of layers of filling spaces by the pile body and a slope, and backfilling the filling spaces with roller compacted soil for multiple times to form a plurality of layers of roller compacted soil layers; 5) after the roller compacted soil is backfilled every time, constructing an unloading plate; and 6) constructing a blind ditch above each layer of unloading plates, wherein one ends of the blindditches are fixedly arranged, and the other ends of the blind ditches extend to penetrate through the pile body and the inter-pile plates to form a drain opening. Therefore the soil pressure distribution of the support structure is adjusted, the dead weight of the support structure is increased, the anti-overturning stability is improved, the support limitation of the support structure is improved, the unloading plates and the inter-pile plates are of reinforced concrete structures and are not prone to corrosion, deformation of the slope can be effectively controlled within the normal servicelife, and the engineering safety is guaranteed.