The objectif of this work is to investigate the effects of the concentation of a plastifier, i.e, Di-Iso-Decyl-Phtalate (DIDP) on the properties of p ol yvi nyl chlor ide ( P V C) po l yme r u s ed i n t he fab r i ca tio n o f el ec tr i ca l cab l e s he at h. T he r e s u l t e d bl e nd ba s e d o n DIDP and P V C resin is prepared by dry blending followed by melt extrusion. The obtained results showed a decrease the tensile strength and shore A hardness when the amount of the used plastifier (DIDP) increases before and after thermal ageing. Furthermore, the strain at the break increases when the amount of the plastifier (DIDP) increases before and after thermal ageing. The thermal stability (deshydrochloration or Beilstein test) is maximal when the c o n cen t r at i o n of t he DIDP plastifier was equal to 45 wt. %.