The ATLAS and CMS Collaborations have observed a 750 GeV diphoton excess at the LHC. I will briefly review the experimental results and theoretical likelihood analyses on the ATLAS and CMS data. I will present its generic implications on particle physics, and then explain the 750 GeV diphoton excess in the Supersymmetric Standard Models (SSMs) in details, especially the Grand Unified Theories (GUTs) with vector-like particles. Moreover, I will present an simple and promising non-suerpsymmetric model where the diphoton resonance(s) can be produced and then decay at tree level.

                                            Host: Prof. Peihong Gu