The invention relates to a tower crane steel foundation suspension installing method. The tower crane steel foundation suspension installing method comprises the following steps that (1) a steel foundation is machined according to the distance between two adjacent structure columns on the outer side of a building, namely the size of the cross section of the structure columns; (2) at the appropriate height, the steel foundation is installed between the two adjacent structure columns and extends to the outer side of the building; (3) after unwinding positioning on the steel foundation, machine legs of a tower crane are welded to the steel foundation; and (4) according to installation instructions of specifications of the tower crane, foundation joints, sleeve supports, rotary assemblies, slewing tower joints, tower top supporting frame assemblies, balance arms, cargo booms and the tower crane are totally installed in sequence. The tower crane steel foundation suspension installing methodis simple, quick, low in cost, short in time, saving in energy and high in environmental protection efficiency; meanwhile, the using manner of the tower crane is expanded, the very high practicability is achieved, and the good method is worthy of popularization.