The Tb2Ti2S2O5 compound belongs to the lanthanide titanium oxysulfides family Ln2Ti2S2O5. The 3D-structure can be schematically described as a 2D-stacking of [Tb2S2] layers alternating with [Ti2O5] ones. The magnetic structure of this compound was determined from neutron diffraction experiments on a powder sample in the 1.4 K - 15 K temperature range. An incommensurate antiferromagnetic long-range order (LRO) occurs at temperatures ranging from 4.1 K to 2.9 K, which turns to a commensurate state below 2.4 K. The evolution of the propagation vector from ki, ⃗ (kx,0,0), kx ≈ 0.46 to kc, ⃗(1/2,0,1/2) is quite unusual. The origin of this unusual change in direction of the propagation vector is not yet explained. On the other hand, a quite large part of the total magnetic moment is involved in a short range ordering (SRO). The refinement procedure taking into account the different coexisting magnetic phases leads to a smooth variation of the total magnetic moment versus temperature.