The invention discloses a main tower area steel truss girder erection method of a base support auxiliary frame beam crane and a base support. The main tower area steel truss girder erection method includes the following steps: a base support and a first all-rotation frame beam crane are installed; a first panel steel truss girder is erected and placed in position; steel truss girders of other panels in a main tower area are erected; and a second all-rotation frame beam crane is assembled in four steps. The base support is composed of a column, a column bearing beam, a vertical connection system, a planar connection system, a front-rear horizontal distribution beam, a bottom anchor device and a distribution beam anchor device. The main tower area steel truss girder erection method has the advantages of being small in construction investment, short in time for using a floating crane, capable of enabling erection of steel truss girder and assembly of the frame beam crane not to be limited by water level or crane height of the floating crane, and capable of reducing longitudinal moving load, decreasing longitudinal moving range and lowering longitudinal moving risk and the like. The base support is simple and novel in structure, specific in stress and capable of remarkably shortening time for using a large floating crane, reduces investment on equipment and has good economic benefits and social benefits.