Cosmic-Rays are very high energy particles, mainly protons, that propagate from their sources to Earth with a power-law spectral distribution, reaching energy of about 1020 eV. Despite the great amount of data collected from their discovery (in 1912), we are not yet able to understand one of the most important issue: what is CR's origin? Where are they accelerated? The best candidate as sources for the Galactic part of CR's spectrum (up to energy of about 1015 eV) are Supernova Remnants but there is the lack of a direct proof of CR's acceleration in their shocks . Our work is focused on this topic. Our aim is a better understanding of the connection between SNR and Galactic CRs through the development of realistic models that can explain experimental data from gamma-ray satellites and particle detectors. So far, the only thing that can be considered as certain is that, for the high-energy astrophysics, “this is a tricky situation” (cit. Freddie Mercury).