Water and oil repellent treatment is done on cotton cloth by pad -dry - baking process. The influences of baking temperature, baking time, pH value and concentration of finishing liquid on water and oil contact position (angle) of fabric are analyzed. The result shows that the optimized water/oil repellent finishing process of cotton cloths is as follows: the concentration of finishing agent is 30g/L, pH value is 6.67, Pick up rate is 80%, and the baking time is 8 minutes under 140℃. After finishing, the oil and water contact position (angle) of the cotton fabrics can reach up to 143.33 degrees and 134 degrees respectively, and at this time the finishing effect is the best. Scanning electron microscopy (SEM) reveals that after water and oil repellent finishing, the external of the cotton fiber becomes smooth, the finishing agent has good film-forming ability, and it has well water and oil repellent performance.