Abstract: According to the development demands of municipal sludge resource utilization and reduction disposal in China, pyrolysis technology can be used to convert municipal sludge into tar, combustible gas and char. The degree of sludge pyrolysis is adjusted by changing the reaction temperature and time. The effects of reaction degrees on the pyrolysis conversion of sludge and the distribution characteristics of pyrolysis products were investigated. The results show that different pyrolysis reaction time has a significant effect on the yield and composition of the three-phase products, and there are some differences with the change of temperature. With the extension of reaction time, the yield of char decreases gradually while the yield of gas increases greatly. At 500 ℃, compared with the reaction time of 0 min, the content of CO₂ and C₂-C₃ increased by 171.9% and 1287.2% in 30 min respectively. However, the yield increase rate of each component in pyrolysis gas at high temperature of 700 ℃ decreased. The CO₂ formed by carbonate decomposition can be gasified with sludge char to form CO. The sludge tar is mainly composed of heavy components, such as distillates with boiling point > 230°C account for more than 90%. The content of light components (< 230 ℃) in tar increased by 131.5 % (500 ℃) with the increase of reaction time, but the yield of each tar fraction changes slightly at 700 ℃. This is because when the temperature is higher (700 ℃), the thermal decomposition is carried out more thoroughly, and the sludge is mainly based on polycondensationafter 600 ℃. By adjusting the pyrolysis temperature and reaction time, the composition and distribution of sludge pyrolysis products can be directionally regulated.