Previous efforts have been made to convert the oil sludge into useful resources such as lower molecule organic compounds and carbonaceous residues by pyrolysis. The liquid products are close to diesel oil; however, they contain a significant amount of vacuum residues, which decrease the qualities of liquid products. For the reuse, conservation and recycling of solid wastes, the effects of using fly ash, oil sludge ash, waste DAY-zeolite and waste polymer of polyvinyl alcohol (PVA) as additives on the possible improvement of the pyrolysis of oil sludge were investigated. For the increase of conversion (X), two weight ratios of 10 and 5wt.% additives provided the offers in the order of fly ash of 10wt.% > PVA of 10wt.% > oil sludge ash of 10wt.% > DAY-zeolite of 10wt.% > fly ash of 5wt.% > DAY-zeolite of 5wt.% > no additives. The addition of additives achieved the improvement of the quality (q) of pyrolysis oil (as sum of light and heavy naphtha and light gas oil) in the order of fly ash of 10wt.% > oil sludge ash of 10wt.% > PVA of 10wt.% > DAY-zeolite of 10wt.% > fly ash of 5wt.% > DAY-zeolite of 5wt.% > no additives. All this information is useful not only to the improvement of a pyrolysis system but also to the better utilization of liquid oil products.