A flow injection two steps elution method on-line sorption and preconcentration system coupled to flame atomic absorption spectrometry (FAAS) was developed for the determination of trace Zn in water samples. The conventional elution procedure was divided into two steps: elution procedure and detection procedure. During the elution procedure, the eluent was pumped into KR by the suction of the peristaltic pump and through PTFE tube instead of peristaltic pump tube. By the new method, the dispersion of the analyte was decreased notably, and high absorbance peak value was achieved. Because the eluent was not through the peristaltic pump tube, the peristaltic pump tube was protected from being eroded. Emptying procedure was added in order to insure the veracity and repeatability of the experiment of every time. With 60 s (sample throughput of 37·h-1) of sampling at a flow rate of 6.0 mL·min-1, an enhancement factor (EF) of 28 (higher than 9 achieved by conventional elution method) and a detection limit (3σ) of 0.35 μg·L-1 were obtained. The precision (RSD, n=11) was 2.1% at the 20 μg·L-1 level. When 0.1 ‰φ triethannolamine was used as masking reagent, the recovery rate was from 98.7% to 99.6%.