Cotton fabric was directly inkjet printed with reactive dye ink, the ink would appear on the permeability of the fabric, the depth of color yield is low, light fastness is poor. Pretreatment agents with different mass fractions had been used to do the pretreatment of the cotton fabric before ink-jet printing, the results showed that: when the concentration of alginate ester or seaweed was between 1.0% -1.5%, the fabrics had the high color yield and the fixation color rate of the dye was the highest. When the amount of NaHCO3 was 3%, the inkjet printing effect of cotton fabrics was the best; color fastness of colors was all good. After Inkjet printing, the best effect can be achieved by steaming the cotton fabrics under the 100 °Csaturated water vapor for 25min: the colors of black, red and yellow of the K / S value were of the maximum, color fastness was fine.