Graft copolymerization of acrylamide (AM) and diallyl dimethyl ammonium chloride (DMDAAC) onto chitosan in inverse emulsion was studied. The effect on Zeta potential and average granularity of synthetic inverse latex of the main reaction conditions such as the proportion of cationic monomer in total monomers, concentration of potassium persulfate (KPS) used as initiating agent were investigated in detail. It was shown that when the weight ratio of chitosan, AM and DMDAAC was 1:6:2, KPS concentration was 4.0mmol/L, NaHSO3 concentration was 2.0mmol/L, stable inverse latex which had optimal performance could be gained. Good retention effect was obtained when a novel organic microparticle retention system composed of the above-mentioned chitosan-AM-DMDAAC inverse latex and anicnic polyacryamide (APAM) was applied to the deink pulp. First Pass Retention retention percentage of deink pulp was improved from 83.2% to 95.0% with the organic microparticle retention system when the dosage of inverse latex was from 0 to 0.4% of absolute dry pulp.