In this paper, the high-speed rotor shaft of the air compressor is repaired by laser cladding and machining. A series of measures to suppress substrate temperature rising are taken during the cladding process. Multiple sets of single-pass and multi-pass lap welding experiments were carried out and tested under the conditions of different laser power and cladding lap ratio, with the scanning speed, powder feeding speed and protecting gas flow rate controlled. The test results show that the cladding effect is optimal with laser power 600w and lap ratio 27.5%. The hardness of the cladding layer is HRC53-56, which is metallurgical bonding with the substrate. The substrate temperature during the cladding process is always maintained below 100 ℃. The cladding layer which is stained by colored penetrant after the repair hasno defects such as cracks and pores. The installation operation requirements are met after the dynamic balance detection and adjustment.