A class of blending function with shape parameter is presented in this paper.It is an extension to the degree′n Bernstein basis function.Based on this blending function

we define a class of adjustable quasi Bézier curve.The blending functions and quasi Bézier curves have the most properties of Bernstein basis and the Bézier curves.Moreover the shape of the quasi Bézier curves with the same control polygon can be adjusted by changing the shape parameter value.Using this method

quasi Bézier surfaces with parameters are constructed.Experiments show that the method given in this paper is intuitive

effective and easy to control.