We report an infrared study on the optimally Te-doped iron-chalcogenide superconductor, Fe_1.03Se_0.5Te_0.5 as a function of pressure at various low temperatures down to 115K. The evolution with pressure and temperature of the mid-IR reflectance spectra shows that by increasing pressure the mid-IR absorption band associated with magnetic order reduces its intensity before it vanishes at 2 GPa. However, overall low temperature reflectance spectral in the mid-IR range indicates drastic changes in the electronic configuration of the system at all pressures up to 5 GPa below 120K. Far IR reflectance measurements at various high pressures show dramatic changes of the IR phonon spectra indicating structural transition below this temperature. Thus our study suggests that structural modification may not be the only parameter establishing the magnetic order in this system.