Previous efforts were made to convert the oil sludge into useful resources such as lower molecule organic compounds and carbonaceous residues by pyrolysis with the carrier gas of N-2. The liquid products (condensates of gases at 298 K) obtained from the pyrolysis of oil sludge are close to diesel oil. However, they contain a significant amount of vacuum residues of about 9.57 wt %, which decrease the qualities of liquid products. In the present study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in the northern Taiwan is used as the raw material for the pyrolysis. The influences of using inexpensive and nonharmful additives on the possible improvement of the pyrolysis of oil sludge are investigated. The additives employed include two groups: (1) aluminum compounds (Al, Al2O3, and AlCl3), and (2) iron compounds (Fe, Fe2O3, FeSO4.7H(2)O, FeCl3, and Fe-2(SO4)(3).nH(2)O). For the increases of conversion X, the additives provide the offers on the order of Fe-2(SO4)(3).nH(2)O > Fe2O3 > AlCl3 > FeSO4.7H(2)O > Al2O3 > FeCl3 > Al > Fe > no additives. It appears that the above additives enhance the reaction rates r when the temperatures T are in 650-710 K, following the orders AlCl3 > Al > Al2O3 > no additives, and Fe2O3 similar to Fe-2(SO4)(3).nH(2)O > FeCl3 similar to Fe similar to FeSO4.H2O > no additives at 710 K. The additives achieve the improvement of the quality q of the oil of pyrolysis (as sum of light and heavy naphtha and light gas oil) on the order of Fe2O3 > Fe-2(SO4)(3).nH(2)O > no additives > Al > FeSO4.7H(2)O > Al2O3 > Fe > FeCl3 > AlCl3. Nevertheless, the additives improve the liquid yields Y on the order of Al > Fe-2(SO4)(3).nH(2)O > Fe > Fe2O3 > FeCl3 > no additives > AlCl3 > FeSO4.7H(2)O > Al2O3. All this information is useful not only to the improvement of a pyrolysis system but also to the better utilization of liquid oil products.