The invention discloses a caisson and pile combined foundation of consolidated subsoil and a construction method of the caisson and pile combined foundation. The caisson and pile combined foundation of the consolidated subsoil comprises the consolidated subsoil, a sand-gravel cushion, a caisson, bored piles, pile bottom grout, top seal concrete and scour protection. The main construction method comprises the following steps: consolidating the foundation with an underwater compaction sand pile or a deep-layer cement mixing pile; laying the sand-gravel cushion on the consolidated subsoil; sinking the caisson with a skirt, pile sinking guide holes and grouting reserved pipes on the sand-gravel cushion; after the caisson is located, constructing bored piles through the pile sinking guide holes; after construction of the bored piles, casting the top seal concrete at the bottom in the caisson; grouting the bottom of the caisson through the grouting reserved pipes at the bottom of the caisson, carrying out pile bottom grouting through grouting pipes in the pile, and at last casting the top plate of the caisson. In the construction process, the scour protection shall be performed around the caisson according to requirements. The caisson and pile combined foundation of the consolidated subsoil and the construction method of the caisson and pile combined foundation, disclosed by the invention, can effectively improve vertical and horizontal bearing capacity of the caisson, and control sedimentation and horizontal displacement of the caisson.