The intensity (pressure) of the reflected shock and its duration (test time) are the two main indicators of the performance of chemical shock tubes. Convergence curves are capable of creating stronger shock under the same initial conditions. However, they may bring in pressure peaks after the reflected excitation that cannot be maintained at a constant level. The main objective of the present study is to construct convergence curves suitable for use in chemical shock tubes with a constant pressure region after reflecting the excitation wave and a waveform distribution with less curvature. Firstly, based on the principles of gas dynamics and excitation wave dynamics, mathematical models with eight different convergence profiles were established. Secondly, a twodimensional model of the shock tube with different convergence curves is constructed. Finally, the waveform distribution of the internal wave system of different chemical shock tubes was investigated, and the change rule of test time and pressure value after the reflected shock wave was revealed. Results show that the convergence curve based on shock dynamics with an inclination angle of 2° forms a longer pressure constant zone after reflected shock wave and the waveform curvature is minimum.