Fabricated stand column, extended foundation and construction method thereof

The invention discloses a fabricated stand column, an extended foundation and a construction method thereof. Fabricated standard layer components of different sizes can be prefabricated in advance according to requirements, the quality and precision of all the components are guaranteed, the components are spliced and connected to form an integral structure of the extended foundation on site according to the actual height requirements, bottom square columns and adjusting square columns are installed on the extended foundation, stand columns with the required height or the required number of standard knots are installed on the adjusting square columns, the adjusting square columns serve as adjusting structures arranged between the stand columns and the extended foundation and are matched with supporting pieces, so that height adjustment within a certain amplitude range can be achieved, different height requirements are met, the height of the stand columns is adjusted after the stand column construction is compl