The invention discloses a deep repairing method of a turbine impeller of a starter. The deep repairing method comprises the follow steps that a turbine impeller entirety, with cracks, of the starter is selected, and a shaft part of the turbine impeller, with cracks, of the starter is removed through a machining method; TC4 titanium alloy materials similar with the materials of the original turbine impeller are selected to machine a new turbine impeller shaft of the starter; the to-be-welded turbine impeller of the starter and the new turbine impeller shaft of the starter are washed to be clean; the turbine impeller of the starter is heated to be 150 DEG C-160 DEG C, and the new turbine impeller shaft of the starter is installed in the turbine impeller of the starter and installed in place; an oxide layer in a welding area of the new turbine impeller shaft of the starter and a turbine impeller assembly of the starter is removed, and cleaning is conducted; the new turbine impeller shaft of the starter and the turbine impeller assembly of the starter are welded; and undamaged flaw inspection is conducted on an overall machined new turbine impeller of the starter. The deep repairing method of the turbine impeller of the starter has the advantages that cost is saved, and usability of the impeller is improved.