The preparation for continuous flow analysis of potassium in tobacco was improved to increase the analytic rate. Namely, the potassium in tobacco was directly extracted with distilled water and then analyzed. Water extraction was compared with traditional digestion, the results indicated that: 1) the average recovery of water extraction was 101.3% and its coefficient of variation was less than 2%; 2) there was no significant difference between the results determined by water extraction and digestion. It was concluded that water extraction could be applied in sample preparation of potassium in tobacco instead of digestion.