Abstract: In order to improve the dyeing properties of cotton fabric via foam dyeing and photocuring, a siloxane oligomer containing unsaturated double bonds was synthesized. A suitable foam system containing yellow anthraquinone dye, siloxane oligomer, photoinitiator of Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide(TPO), and surfactant of sodium dodecyl sulfate(SDS) for foam dyeing of cotton fabrics was designed. The chemical structure and molecular weight distribution of siloxane oligomers was analyzed by 1H-NMR and GPC. The chemical structure of siloxane oligomer and dyed cotton fabric was characterized by FTIR. The morphology of dyed cotton fabric was observed by SEM. The effects of amount of oligomer, amount of dye, concentration of surfactant, amount of photoinitiator on foam performance and dyeing performance were discussed. The results showed that K/S value of 5.70 , the colo fastness to soaping and to dry /wet rubbing of 4-5, ultraviolet protection factor >50 and water contact angle of 110.1°were achieved under the conditions of the concentration of dye solution of 30 g/L, the ratio of oligomer/dye of 2:1, the concentration of SDS of 2 g/L, TPO amount of 5% on the mass of monomer, and UV irradiation time of 5 min. The siloxane oligomer undergoes radical polymerization through the unsaturated double bonds on the side groups and silanol group coupling and crosslinking to achieve color fixation and gives the fabric good hydrophobic properties and anti - ultraviolet properties.