The formula of a kind of sugar-free cake with Rhiizoma dioscoreae and buckwheat was prepared. The optimal formula and factors were ascertained by single factor experiments and orthogonal experiment,which was mixed flour (buckwheat flour∶wheat flour=4∶6)100g, Rhiizoma dioscoreae pasty 70g, xylitol 40g, baking powder 1.7g, egg 150g, soybean oil 20g, cake oil 3.5g, fresh milk 20g, baked at 180℃ for 20min. In this condition, the sugar-free cake with Rhiizoma dioscoreae and buckwheat was produced withgolden color,and delicious and pure taste.