The Broer-Kaup equation is one of many equations describing some phenomena of
shallow water wave. There are many errors in scientific research because of the
existence of the non-smooth boundaries. In this paper, we generalize the
Broer-Kaup equation to the fractal space and establish fractal variational
formulations through the semi-inverse method. The acquired fractal variational
formulation reveals conservation laws in an energy form in the fractal space and
suggests possible solution structures of the morphology of the solitary waves.