An experiment was performed to measure the axial pressure fluctuation of the vortex quick separation system with annular pre-stripper. In order to give suggestions to the operation stability of actual industrial device through analyzing the pressure fluctuation characteristics and mechanism. As is shown in the experimental results, the axial pressure fluctuations have great similarity in the shape of the curves. The strength of the fluctuation increased with ejection gas velocity and the particulate mass flow rate increasing. Through the wavelet analysis, the frequency range of this device is approximately 1.5~12.5 Hz with a period of 7~10 s. It is found that there is an enormous pressure fluctuation above the quick separator and a vortex zone is found there. The circumferential pressure pulsations are basically the same, and the radial r/R=0.4~0.7 has a bigger vortex zone and the pressure fluctuation intensity is lower. As for industrial device operating stability, it is suggested that the injection gas velocity of the quick separation head is in the range of 18~24 m/s and the riser particle mass flow rate is more than 90 kg/(m2?s), the device can run stability.