The Sun is an intense and steady source of gamma rays, likely due to hadronic interactions between Galactic cosmic rays and the solar atmosphere.The gamma-ray flux measured by Fermi, however, is much larger than previous theoretical estimates. I will discuss recent observational results that revealeven more surprising features, including time variability that anticorrelates with the solar activity, a hard spectrum, and a strange spectrum dip, etc. In the near future, very high-energy observation by HAWC/LHAASO and neutrino observation by IceCube may help understand the underlying physics. Cosmic-ray interaction with the Sun can be a new probe of cosmic rays in the solar system and solar atmosphere; a better understanding is important for neutrino and dark matter searches from the Sun.