Abstract-The monitoring and early-warning of abnormal events in public places is an important part of the public security research. But nowadays, the monitoring way is basically video surveillance, and the judgement and analysis of abnormal events is based on the video content. This single way has low accuracy and analytic algorithms have some limitations, so the single audio analysis method can't offer timely and effective early-warning. Taking a sudden car fire event for example, this article combines the audio analysis and video analysis to judge abnormal events and also designs an new surveillance system, offering an effective way to early-warning.