HESS J1731-347 is the first supernova remnant (SNR) that has been discovered based on TeV observation. First an unassociated source discovered in the survey of the Galactic plane by the HESS experiment, it has later been identified as a new SNR (through radio and X-rays observations) and is now the 4th object in the restricted club of SNRs with a TeV shell morphology. This new SNR shares many similarities with the brightest TeV SNR RX J1713.7-3946: comparable TeV luminosities, lack of thermal X-ray emission and the remnants from a gravitational core collapse (compact objects observed at the center). Using the spectral and morphological information derived in TeV, the GeV emission of the SNR is investigated with data from the Fermi Gamma-ray Space Telescope in order to test whether the nature of the gamma-ray emission is of leptonic (as it has been found for RX J1713.7-3946) or hadronic origin.