Photoluminescence and photoluminescence excitation spectra of nanosize poly(di-n-hexylsilane) embedded in the SBA-15 with 6 nm diameter pore were investigated in the temperature range of 10-290 K We clearly demonstrate the thermochromic transition at 265 K between trans- and gauche- conformations of an isolated polymer chains embedded in the nanoporous material. Existence of the polymer chain having trans-conformation in a separate pore of 6 nm diameter was prooved. The location and packing of the polymer chains in this pore was simulated using the quantum chemistry calculations in the cluster approximation. The investigation of the polarized luminescence dynamics of the nanosize polymer with pore diameters of 6 and 10 nm has shown that the polymer chains are aligned by embedding.