Five metal complexes of Cu(II), Cd(II), Zn(II), Ni(II) and Sn(II) with {4-(Benzylidene-amino)-5-pyridin-4-yl-4H-[1,2,4]triazole-3-thiol}, of Schiff base ligand (L), were prepared in alcoholic medium. The ligand (L) and its metal complexes were characterized qualitatively by using: FTIR, UV-visible spectroscopy, magnetic susceptibility, conductivity measurements and 1H NMR only for ligand. The ligand acted as bidentate which coordinated to the metal ions through sulphur and nitrogen of Azomethine group. According to the spectral data of the complexes a tetrahedral geometry was suggested for these complexes, except Cu(II) complex which exhibited octahedral geometry distorted to square planar structure. The metal complexes were used to enhance the photostabilization of PVC contains a concentration of ML2 0.5 % by weight. The photostabilization of PVC films were studied at room temperature under irradiation of light with λ=313 nm and an intensity of 7.75 X 10-7 einstein dm-3 sec-1. The photostabilization activity of these compounds was determined by monitoring the carbonyl (ICO), polyene (Ipo) and hydroxyl (IOH) indices and weight loss method with irradiation time. It was found that the (ICO), (Ipo) and (IOH) indices values increased with irradiation time and this increase found to depends on the type of additives. The surface morphology for these films was studied during irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PVC films was also evaluated. The following trend was obtained for the photostabilization effect on PVC films in presence of additives as shown below: CuL2 , CdL2 , ZnL2 , SnL2 , NiL2 Increasing the photostability according to the obtained experimental results, mechanisms were suggested,depending on the structure of the complexes.