The invention relates to the technical field of transformer construction, in particular to a transformer foundation stepless heightening steel support and a construction process thereof. The transformer foundation stepless heightening steel support comprises a support body. The lower end of the support body is provided with a base. The base is provided with a plurality of fixing foot bolts. The upper end of the base is provided with a lower supporting column. A rotary shaft is inserted at the upper end of the lower supporting column. The outer side of the rotary shaft is provided with a bidirectional adjusting bolt. The upper side of the rotary shaft is provided with an upper supporting column. The upper supporting column is provided with a plurality of locating holes. Locating and supporting devices are arranged on the locating holes. According to the transformer foundation stepless heightening steel support, the height and flatness of a steel plate can be quickly adjusted through thebidirectional adjusting bolt and the locating holes, and the error can be controlled within one millimeter. Compared with an original construction process, the construction process provided by the invention has the advantages that the construction cycle is short, the construction cost is low, and the construction quality can be ensured.