Abstract: Using de Casteljau algorithm，The allthors derive the sufficient and necessary conditions of a developable surface being a ruled surface generated by curves of n degree and m degree respectively as its two boundaries，point out the number of constraint conditions of a ruled surface，and present a new method of designing ruled surface of（2，3） degree.Experimental results show that the design method proposed is easy to design and easy to control the surface shape.

摘要： 利用de Casteljau算法，得到两条边界曲线分别为m，n次的空间曲线所生成的直纹面为可展曲面的充分必要条件，给出了可展曲面所满足的约束条件的个数，提出了（2，3）次可展曲面的一个新的设计方法。数值实验说明，该方法设计简便，易于控制曲面形状。