Petrochemical industry bio-sludge was pyrolyzed to investigate the composition and pore size distribution of pyrolytic residue. Results indicated that the carbon, nitrogen, and hydrogen concentrations could be reduced after an increase in pyrolytic temperature. The trace element analysis indicated that Al, Ca, Fe, Mg, K, Cu, Sr, and Sb concentrated during the pyrolytic process. When forty grams of pre-dried sludge were pyrolyzed at various pyrolytic temperatures, the transfers from the gas phase to liquid phase to residue were from 21.2 to 36.0%, from 49.0 to 70.0%, and from 8.3 to 16.5%. Results of the pore size distribution examination indicated that the mesopore had the greatest effect on the bio-sludge pyrolysis, The optimal pyrolytic temperatures and times were approximately 800 degreesC for 30 min and 900 degreesC for 10 min. The conceptual model can reasonably explain the pore structure development during the pyrolysis process.