The invention discloses a chain tilling machine. The chain tilling machine comprises a machine frame, a transmission shaft fixed to the machine frame, transmission gears arranged on the transmission shaft, a square beam hinged to the transmission shaft, tensioning frames connected with the square beam, driven gear shafts, driven gears, chains, tilling blades and hydraulic rods, wherein the driven gear shafts and the driven gears are arranged on the tensioning frames, the chains are used for connecting the transmission gears and the driven gears, the tilling blades are arranged on the chains, and the two ends of each hydraulic rod are hinged to the square beam and the machine frame respectively. The square beam can buffer and reduce reverse impact force on the machine when the tilling blades collide with hard objects in a field, a transmission device of the machine is protected, and the service life of the machine is prolonged. The tensioning frames which are independent of one another easily increase the depth of soil loosening. The chain tilling machine can smash crop straw and weed at a time and mixes the smashed crop straw and weed into soil, and completes deep loosening, clod disintegrating, land formation and other tillage operation.