Abstract：In 2013, the IceCube Neutrino Observatory at the geographic South Pole detecteda diffuse astrophysical neutrino flux, marking the dawn of high-energy neutrino astronomy. Since then, the campaign of hunting for astrophysical neutrino sources has been on. On September 22, 2017, the IceCuberealtime alert system detected a 290 TeVmuon neutrinoevent, which triggered follow-up observations from more than 20 multi-wavelength telescopes around the world. The event was eventuallytraced back to a flaring blazar TXS0506+056, approximately 4 billion light years away. I will talk about the multi-messenger observation of the blazar neutrino event and its implications.