An investigation of Pentachlorophenol (PCP) in South Drainage Canal and Haihe Estuary, Tianjin, China was carried out from 1998 to 1999. PCP was found in each sample of the surface microlayer, subsurface water, sediment and air. The waste drainage from a PCP-producing plant was the main pollution source of PCP to Haihe Estuary. The enrichment phenomenon of PCP in the surface microlayer was reported for the first time. The maximum enrichment factor was 4.11. A multimedia (including air, the surface microlayer, water and sediment) fugacity river model was established and successfully applied to fate data for pentachlorophenol in South Drainage Canal. The results showed that under steady state, 97.09% of the loaded PCP was removed by advective outflow into Bohai Bay and 2.46% was by the biodegradation in the water phase. The residue of PCP in South Drainage Canal mainly distributed (99.56%) in the water phase. The discharge rate of PCP from South Drainage Canal to Bohai Bay was 53.4 kg/h.