Abstract：sewage sludge based activated carbon (SSAC) was prepared by taking dewatered sewage sludge as raw material with ZnCl2 as activating agent. BET test, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were utilized to analysis all of the Acs. Using dynamic adsorption system and distiller, adsorption performance of SSAC was compared with some commercial activated carbons (CACs), and the performances for desorption of formaldehyde in different activated carbons were investigated by using thermogravimetry. The adsorption capacity of SSAC, in formaldehyde concentration of 498, 0.41mg/m3, could achieve 74.27, 7.62mg/g and the removal efficiency was 83.72% and 89.56 %, respectively, and such was comparable with CACs’. Especially, in 0.41mg/m3, the result of SSAC exceeded that of CACs. The BET specific surface area of SSAC was 509.88m2/g and its nitrogen adsorption isothermal curve belonged to I-B in the BDDT classification. SSAC had high proportion of micropores, which made it more suitable to adsorb low concentration formaldehyde. The FTIR spectra indicated that on the surface of SSAC, there were lots of nitrogen-containing groups, especially amino-groups. These groups might form chemical reaction centers. However, the Derivative thermogravimetry (DTG) curves of the activated carbons which had adsorbed formaldehyde indicated that the major adsorption of formaldehyde on activated carbons was physical adsorption.