Recently, an excess of events in diphoton channel with invariant mass of about 750 GeV has been reported by the ATLAS and CMS Collaborations. Considering it as a tantalizing hint for new physics beyond the Standard Model (SM), we propose a simple extension of the SM with an additional doublet Higgs H and a singlet s. We consider the neutral component H 0 of H as the 750 GeV resonance, and assume that s is lighter than 2.6 GeV. In particular, H 0 can be produced at tree level via qq production, and decay into a pair of s at tree level. And then s can decay into a pair of collimated photons, which cannot be distinguished at the LHC. We show that the diphoton production cross section can be from 3 to 13 fb, the decay width of H 0 can be from 30 to 60 GeV, and all the current experimental constraints including dijet constraint can be satisfied.