This study was performed to investigate the retention(first-pass retention, solid and ash contents) and the cationic demand(CD) amounts according to the addition of various retention aids. For the purpose of this study, polyethyleneimine(PEI, SC) as a retention aids were used. De-inked pulp(100% DIP) and headbox stocks(containing headbox fines) obtained from de-inking process were treated with these retention aids. In the case of retetion, PAM treament was better than those of PEI(SC) treatment. On the contrary to the retention, PEI(SC) was greater than those of the other retention aids(NC, UN and SG-PAM) in the ability of anionic trash removal.