Abstract: The paper proposed the potentiometrie titration - online test to determine the melamine in feed. The sample solution was prepared after the sample was processed, then the potentiometrie titration was conducted with sulfuric acid standard liquid, and the specially designed program was used to collect titration data and titration curve was dynamically displayed, and data processing with computer. The detection results showed that the method was in simple and sensitive operation with correct outcome and low analysis cost, and was suitable for routine testing.