  In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu
extension of the two-Higgs-doublet model by introducing a top partner
($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is
identified as the heavy CP-even Higgs boson ($H$), which can be sizably
produced via the QCD process $pp \to T\bar{T}$ or $pp \to B\bar{B}$ followed by
the decay $T\to Ht$ or $B \to Hb$. The diphoton decay rate of $H$ is greatly
enhanced by the charged singlet scalars predicted in the Zee-Babu extension and
the total width of $H$ can be as large as 7 GeV. Under the current LHC
constraints, we scan the parameter space and find that such an extension can
account for the observed diphoton excess.
