  The recently observed diphoton resonance around 750~GeV at the LHC Run-2
could be interpreted as a weak singlet scalar. The scalar might also decay into
a pair of $Z$-boson and photon. The $Z$-boson is highly boosted and appears as
a fat jet in the detector. We use the jet substructure method to explore the
possibility of discovering the singlet scalar in the process of $pp\to S\to
Z\gamma$ in the future LHC experiment.
