Abstract: Cationic polyacrylamide with quaternary ammonium group was used for cotton pretreatment with dip-pad-bake method and the obtained cotton was applied to salt-free dyeing of reactive dyes. The adsorption behaviors of C.I. Reactive Red 195，C.I. Reactive Red 19 and C.I. Reactive Yellow 145 on cationised cotton were investigated. Langmuir and Freundich adsorption models were applied to describe the equilibrium isotherms and isotherm constants were obtained. Langmuir-type adsorption isotherms were determined for reactive dyes on cationised cotton and the pseudo-second-order model provided a very good fitting for the three reactive dyes. The thermodynamic parameters including change in free energy（ΔG），enthalpy（ΔH），and entropy（ΔS）were also calculated and discussed. The color yield and fastness properties of the dyes on both fibers were also investigated and the satisfactory results showed the feasibility of the pretreatment method.