Nitrogen migration from sewage sludge (SS) to gaseous products is one of the factors preventing the use of pyrolysis technologies. A new route for nitrogen recovery by capturing NH3 using acidic gas released from SS pyrolysis was investigated in this study. SS was pyrolyzed from 30 to 800 °C with heating rate of 10 °C/min firstly, and thermogravimetry coupled to Fourier transform infrared (TG-FT-IR) analysis was conducted for gaseous products characterization with different pyrolysis temperature. Then, nitrogen containing compounds (NCCs) with the yield of 1.72 wt% was obtained from the gaseous products during SS pyrolysis at 400 °C. The results of elements analysis and FT-IR characterization indicated that the NH3 in the gaseous products was recovered in the form of NH4HCO3. The results provide valuable information and insight into pollutant components recovery in gaseous products during SS pyrolysis, and future integration systems of SS pyrolysis and nitrogen capture technologies may be developed for nitrogen recovery from gaseous products.