The invention relates to a processing method of salt-free dyeing through activated dye, which includes the steps of: (1), acid pickling and enzyme washing of cotton fabric after the pretreatment of scouring and bleaching; (2) mixing water with organic solvent at volume ratio of (1:4)-(1:9) to form a mixed solution, and then adjusting the pH value of the mixed solution; and (3)dyeing the pretreated cotton fabric in 20-30 DEG C activated dye by using the mixed solution, then carrying out water scrubbing, acid pickling, soaping, hot-water scrubbing, color fixing and softening on the dyed cotton fabric, and finally recovering the solvent. With the processing method, the adsorption rate and the equilibrium adsorption amount of the activated dye are improved, and environmental and ecological problems caused when large quantity of inorganic salt is used are completely solved. In the dyeing process, the input of inorganic salt is omitted, so the operational techniques and the labor intensity in the dyeing process are effectively simplified and the production cost is reduced. Through a solvent recovery system, the solvent contained in the dyeing residue of the hydrosolvent is recovered for cycle use. Therefore, the recovery and the recycling of the resource are realized, the production cost is saved and the pollution to the environment is alleviated.