Based on the fact that 6-propy-2-thiouracile（PTU） could strongly enhance the electrochemiluminescence（ECL） of tris（2,2’-bipyridine） ruthenium（Ⅱ）（Ru（bpy）2+3）,a new flow injection analysis method with a homemade electrochemiluminescence（FI-ECL） detector was proposed for the first time.The experimental parameters those may influence the ECL intensity of the Ru（bpy）2+3/PTU system（such as voltage signal mode and applied potential,pH of buffer solution,flow rate of the carrier solution,and concentration of Ru（bpy）2+3solution ） were investigated.The optimum conditions for the FI-ECL detection of PTU were obtained and the possible mechanism of the ECL system was suggested.The results showed that in 0.1 mol?L-1 pH 12.0 H3PO4-NaOH buffer solution,when the carrier solution’s flow rate was setted at 1.5 mL?min-1,the strongest ECL intensity enhancement could be realized at potential of +1.50 V in the present of 1.0×10-4 mol/L Ru（bpy）2+3.Under this optimal condition,the linear range of PTU was 2.0×10-7-1.0×10-4 mol/L with a correlation coefficient of 0.998 6 and a detection limit(S/N=3) of 1.3×10-8 mol/L.The relative standard deviation（RSD,n=3） for 1.0×10-6 mol/L PTU standard solution was 1.2%.The method was simple,rapid and sensitive,and was successfully applied in the determination of PTU in spiked animal feeds.