Abstract: Hydroxypropyl terminated fluorinated polysiloxane was synthesized via hydrosilylation by hydrogen terminated fluorinated polysiloxane and allyl alcohol as raw material and chloroplatinic acid as catalyst, and applied in preparing for modified waterborne polyurethane. Influence of synthetic factors on the double bond conversion were researched, the synthesis conditions were optimized, the chemical structure of synthesis product was characterized by FTIR、1H-NMR and GPC, the properties of emulsion and film of modified waterborne polyurethane and coated fabric were measured. The results showed that the side reaction inhibitor could effectively prevent for the side reaction. the optimal synthesis conditions of hydroxypropyl terminated fluorinated polysiloxane were that the dosage of side reaction inhibitor was 0.2 %, the dosage of catalyst was 60ppm, the reaction temperature was 75 ℃, and reaction time was 4 h. The particle size of the emulsion of waterborne polyurethane was 45nm, the water contact angle and the water absorption of the film were 106.8 °and 28.1 % respectively. Compared with the unmodified polyurethane, the water resistance of the fabric coated with modified waterborne polyurethane was improved significantly.