We give an overview of the VBF analysis of the Higgs boson decaying into a pair of W bosons, with about 36fb^-1 of proton-proton collisions at center-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC. One of the leading background processes is the Z boson decaying to a pair of leptons, and our study focuses on the results associated with data and Monte Carlo sample in the Z→ tautau control region of this analysis.