Bottom-layer tower drum with pre-installed bottom platform and installation method of bottom-layer tower drum

The invention discloses a bottom-layer tower drum with a pre-installed bottom platform and an installation method of the bottom-layer tower drum. The pre-installed bottom platform is arranged in a tower drum main body, and a bottom platform supporting frame is built after the bottom-layer tower drum is integrally installed, so that the bottom platform does not need to be built independently in a wind field; and only the bottom platform supporting frame needs to be built for the bottom platform in the bottom-layer tower drum after the bottom-layer tower drum is installed and fixed, so that high-risk operation of building the bottom platform is avoided. A first supporting beam and a second supporting beam of the upper platform frame are detachably and fixedly connected, so that the upper platform frame can be conveniently detached, and hoisting for large electrical equipment such as a converter is facilitated. The problem that a bottom platform in a bottom-layer tower drum in the prior art is prone to being aff