Abstract: In order to reveal the mechanism of salt-free dyeing of HBP—NH_2 grafted oxidized cotton fabrics(HGCF) with reactive dyes,the ζ-potential of HGCF in the liquid phase,dyeing thermodynamics,dyeing dynamics and hue changes of HGCF dyed with reactive dyes were examined.As a result,the ζ-potential of the HGCF is positive at pH′s lower than 6.5.The dyeing behaviour of reactive brilliant yellow A-4GLN on HGCF was found to follow a Langmuir-type adsorption curve,and the value of adsorption constant and saturated adsorbing capacity decreased when the temperature was raised,the dyeing entropy is(-4.51 kJ/mol.) Compared to ungrafted cotton fabrics,HBP—NH_2 grafted oxidized cotton fabrics can improve the speed of dyeing,the equilibrium dye uptake and the diffusion coefficients.Meanwhile,there was slight hue changes on HGCF dyed with reactive dyes in salt-free dyeing.