Objective To establish a determination method of phthalates in the drinking water used to monitor the pollution level of phthalates in the drinking water of Beijing. Methods 23 samples from drinking water plants in Beijing were determinated by GC-MS, using selective ion mode (SIM)with high sensitivity and internal standard quantitation method with high accuracy. Results In all samples, di(2-ethylhexyl) phthalate (DEHP) was detected out and the highest concentration was 24.5 ?g/L, dibutyl phthalate (DBP) was detected out in 7 samples and the highest concentration was 11.1 ?g/L, The other 3 kinds of phthalate were not detected out. The detection limit of DEHP and DOP was 8.0 ?g/L, DMP, DEP, DBP was 0.3 ?g/L, The recovery rate were 71.7%-96.0%, RSD were 2.8%-9.0%. Conclusion The main pollutants of phthalates are DEHP and DBP in drinking water of Beijing, GC-MS is suitable for determination of phthalates in drinking water.