The O2 follow-up campaign of gravitational wave candidate (GW) events was intensive with the collaboration of 95 groups in astronomy and astro-particle physics. Since the size of the localization error of GW is quite large, the follow-up strategy for finding counterpart of GW alerts is quite complex. However, the joint accomplishment was rewarded with the first multi-messenger probe of the merger of a binary neutron stars (GW170817), an associated electromagnetic counterpart as gamma-ray burst (GRB170817A) and bright multiwavelength isotropic emission. In my talk, I will present the O2 campaign and the EM follow-up strategies especially with SVOM telescopes. I will enlight significant muti-messenger results associated with GW170817 in particular information obtained from gravitational signal. I will finally show expectations for the future of multi-messenger astronomy with arrival of new projects especially the SVOM satellite.