The machining of continuous short blocks is a hot and difficult point for CNC machining. In this paper, a data compression algorithm based on the Bézier curve was proposed. First, the areas suitable for compression were screened out based on the geometric characteristics of continuous short blocks. Then, G01 points in each area were converted to special 3 order Bézier curves. To decrease the fluctuation of curvature and increase the compression ratio, the least square method was chosen to fit points. By adjusting the control points and inserting transition curves, the machining path was made G2 continuous. The fitting error was estimated by 2-order Taylor formula. Without iteration, the algorithm was realtime. The experiment proved that the compression ratio was high. The errors estimated by Taylor formula was extremely close to the real ones, indicating that the fitting accuracy could be controlled effectively.