The invention provides a transformer installation foundation and a transformer substation. The transformer installation foundation comprises a bottom plate fixedly installed on the ground, and supporting piers matched with a transformer. The supporting piers are prefabricated parts. The bottom plate is connected with the supporting piers through connecting assemblies. According to the technical scheme of the transformer installation foundation and the transformer substation, the bottom plate is poured on the site, the supporting piers are prefabricated, and the bottom plate and the supporting piers are manufactured separately and are connected and installed through the connecting assemblies on the site during installation; by means of the design, the construction period is obviously shortened at first, the requirement for the design of the bottom plate is not high, design and construction can be conducted in advance, therefore, the bottom plate of the transformer installation foundation can be constructed by adopting design data which do not need to be defined, the engineering construction efficiency is effectively improved, and the construction period is shortened; then standardizing is easy, the supporting piers appear in the form of transformer components, so that the situation that positioning of the transformer is inaccurate due to a design mistake is avoided, design change is reduced, and the engineering cost is reduced; and meanwhile, the supporting piers can be adjusted freely when the transformer is installed, so that the effect that supporting pier positioning is consistent with the reality of the transformer is ensured.