The invention relates to the technical field of indoor construction, and discloses an auxiliary tooling and method for construction of an indoor distribution box. The tooling comprises a steel pipe, an adjusting sleeve and a mounting frame, wherein a top support mechanism comprises a threaded rod and an adjusting seat with an internal thread; the threaded rod is inserted into the bottom of the steel pipe, the top surface of the adjusting seat is contacted with the bottom end of the steel pipe, the foundation of the ground supports the the bottom of the threaded rod, and the top of the steel pipe is used for jacking the indoor top; the vertical position of the steel pipe can be adjusted through the adjusting seat; an adjusting sleeve sleeves on the steel pipe and is provided with a threadedhole; the height of the adjusting sleeve can adjusted along the length of the steel pipe and the adjusting sleeve is fixed on the steel pipe through locking screws; a mounting frame is fixedly arranged on the adjusting sleeve and is used for fixedly installing the distribution box. the distribution box can be conveniently supported in the position with a design height, the vertical adjustment range of the adjusting sleeve is large, the installation height change of the distribution box can be adapted, the installation process is not influenced by other professionals, the operating space of the pipeline and fitting box is large, the gap between the periphery of the distribution box and the masonry wall body is small, a large amount of filling work is not needed.