This paper presents a method of parameterization for online freehand drawing objects based on a piecewise cubic Bezier curve approximation. The target is to represent sketches in a compact format within a certain error tolerance with lower computation to be practically adaptable for the online graphics input. A set of user’s intended breakpoints in digital ink is firstly produced in terms of pen speed and local curvatures. Each of strokes of a skechy shape is then parameterized by the optimization of piecewise Bezier curve approximation to minimize the fitting error between stroke path and the curve. The experimental results show both effective and efficient for a wide range of drawing graphic objects.