Three waste water treatment plants (WWTPs) in Beijing were selected as cases to study the occurrence and fate of phthalates. Contents of di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di-butyl phthalate (DBP), butyl-benzyl phthalate (BBP), di-octyl phthalate (DOP) and di-(2-ehtylhexyl) phthalate (DEHP) in influent, effluent of secondary setting tank and excess sludge in those WWTPs were determined. The mean concentration of DMP, DEP, DBP and DEHP are 0.98, 0.21 x 10(2), 0.27 x 10(2) and 0.15 x 10(2) microg x L(-1) respectively. BBP and DOP were not found in those WWTPs. Only DBP and DEHP were detected in dewatered sludge with mean concentration of 0.37 microg x kg(-1) and 0.31 x 10(3) microg x kg(-1) DW. The removal efficiency of DMP, DEP, DBP and DEHP varied from 68.3% -82.6%, 94.5% - 98.2%, 74.7% -95.0% and 90.5% -90.7% respectively. The main removal mechanism should be biodegradation and volatilization to the air. Higher concentration of DBP and DEHP in effluent and dewatered sludge should be concerned.