This study aims to evaluate the flocculation characteristics of reed stock under different retention systems using image processing. A two-step methodological approach was used to compare the effectiveness of various retention additives. First, the Dynamic Drainage Jar and the Pulmac Permeability Tester were employed to assess the retention and drainage of reed stock with the retention aids of Cationic Polyacrylamide and Cationic Starch. Then, a stock flocculation image analysis system was applied to examine the structural characteristics of flocs, focusing on floc area and intensity as key indicators. Finally, the relationship between stock flocculation and paper formation quality was analyzed and discussed. This combined approach provides a comprehensive understanding of how different retention systems influence reed pulp behavior, helping to optimize the use of non-wood fibers in papermaking.