At first, new pendant Schiff base PVC-en-3MSSB was prepared by modification of PVC at the presence of ethylene diamine and 3-methoxy salicylaldehde (3MS). Then, from the reaction of PVC-en-3MSSB and Cu(OAC)2 or VO(acac)2, PVC pendant complexes PVC-en-3MSSB-Cu (1) and PVC-en-3MSSB-VO (2) were prepared. All compounds were characterized by FT-IR, XRD, TGA, DTA and TEM. FT-IR and XRD results confirmed the preparation of all compounds. TGA results show that the stability of complex 1 is higher than 2 and PVC-en-3MSSB. In addition, the catalytic properties of the complexes in Knoevenagel condensation for synthesis of 4-hydroxysalicydenebarbituric acid are investigated and the results show that the vanadium(IV) complex has a better catalytic properties.