Due to the surface scratch, wear or cracks, the performance and dimension of high-speed train wheelseat axle reduce to a level that cannot meet the design requirement after a period of service. Reasonable and efficient maintenance of those worn and valuable parts yields both economical and ecological benefit. In this study, we focused on the feasibility of using extreme high-speed laser material deposition (EHLA) for the repair of full-scale high-speed train wheelseat axle. To this end, AISI 4140 powder particles were selected as additive materials, and suitable process parameters were determined for the production of reduced test pieces. To investigate the possibility of transferring the process parameters determined through reduced piece testing to the full-scale wheelseat axle, finite element (FE) analyses were conducted. In these analyses the temperature distributions for different diameters of substrate with same process parameters were compared, and the results indicate that the process parameters obtained from the reduced sample studies can be transferred to the repair of full-scale axles. On the other hand, however, to consider the effects of thermal history on the clad properties, supplementary heating treatment should be carried out during the EHLA process.