Abstract: According to the analysis results of the connection performance of the high-speed toolholder under different interference amounts and the distribution law of the cone surface contact stress at different speeds, a design method of the high-speed toolholder with cone surface containing sectionally drilled holes is proposed. The cone surface is divided into three equal sections according to the length of the generatrix on the cone, and a set of blind holes are evenly distributed circumferentially at each section. By adjusting the number and size of the blind holes, the cone surface of the toolholder reaches a certain flexibility. The influence of blind hole opening parameters on the contact stress and flexibility of the toolholder cone surface is elucidated, and the parameter optimization range is proposed. The design case of cone segmented opening based on HSK-E50 is given, and the limit speed and contact stress distribution are analyzed by FEM. The results show that compared with the prototype toolholder, the limit speed of the new toolholder is increased by about 10.79%, and the contact stress distribution of the cone surface is significantly uniform.