In view of circular vibrating screen used widely in coal preparation plants at present, the vibration characteristic and working condition of circular vibrating screen was discussed by establishing mechanical model and doing dynamic analysis. And the influence factors of process performance were found out. The stable operating conditions of circular vibration screen was puts forward. All of these can provide theoretical basis for vibrating screen design, correct use and reasonable maintenance. Furthermore, it would be of great significance to improve efficiency of screening and extend service life of screen machine in coal preparation plants.