Abstract: By using the event study method, this paper adopts 118 samples of industrial accidents and natural disasters occurred in China during the period 2003-2013 to investigate the impact of these kinds of event on the Chinese stock markets. We find that: (1) Compared with the bull market, the event occurred in the bear market has longer negative impact. (2) The impact of production accidents is more serious than that of natural disasters which present different effects in stages. (3) Different industries suffer from different degrees of effect. Particularly, the event almost has no negative impact on the industry of power, heat, gas and water. (4) Comparatively, the impact of event on small firms is more serious in a short time, but big firms subject a longer effect period.