  We explore the discovery potential of Higgs pair production at a 100 TeV
collider via full leptonic mode. The same mode can be explored at the LHC when
Higgs pair production is enhanced by new physics. We examine two types of fully
leptonic final states and propose a partial reconstruction method. The
reconstruction method can reconstruct some kinematic observables. It is found
that the $m_{T2}$ variable determined by this reconstruction method and the
reconstructed visible Higgs mass are important and crucial to discriminate the
signal and background events. It is also noticed that a new variable, denoted
as $\Delta m$ which is defined as the mass difference of two possible
combinations, is very useful as a discriminant. We also investigate the
interplay between the direct measurements of $t\bar{t} h$ couplings and other
related couplings and trilinear Higgs coupling at hadron colliders and
electron-positron colliders.
