Abstract: A high speed separation and preconcentration method in a knotted reactor coupled with flame atomic absorption spectrometry was developed for the determination of dissolved trace Zn in seawater with different salinity.This new method was based on the air mixing sorption flow injection (FI) on-line preconcentration procedure in a knotted reactor (KR) coupled with flame atomic absorption spectrometry (FAAS).The preconcentration flow rate was 6.0 mL/min, preconcentration time was 60 s.When the 20μg/L Zn solution was detected, the enrichment factor (EF) was promoted from 9.4 to 23.9 compared with the traditional method; The detection limit(3σ) was 0.31μg/L for Zn; The sample throughput was 40/h, and the relative standard deviation(RSD, n=11) was 2.1% for Zn.The method has been applied to the determination of dissolved trace Zn in seawater with different salinity with the recovery from 95.4% to 97.2% and can satisfy the determination requirements of dissolved trace Zn in seawater with different salinity at estuary.