Using X-ray diffraction and differential scanning calorimetry (DSC), the structure and the crystallization mechanism of SeO.8 Teo.2 chalcogenide glass has been studied. The structure of the crystalline phase has been refined using the Rietveld technique. The crystal structure is hexagonal with lattice parameter a = 0.443 nm and c = 0.511 nm. The average crystallite size obtained using Scherrer equation is equal 16.2 nm, so it lies in the nano-range, From the radial distribution function, the short range order (SRO) of the amorphous phase has been discussed. The structure unit of the SRO is regular tetrahedron with (r2/r1) = 1.61. The Se0.8 Te0.2 glassy sample obeys the chemical order network model, CONM. Some amorphous structural parameters have been deduced. The crystallization mechanism of the amorphous phase is one-dimensional growth. The calculated value of the glass transition activation energy (Eg) and the crystalliza¬tion activation energy (Ee) are 159.8 ± OJ and 104J ± 0.51 kllmal, respectively .