The relationship between public attention and stock has been researching for years in the field of behavioral finance. This paper studied the effect of public attention on excess return under extreme market condition of the 4-day circuit-breaker period of China in 2016. After constructing the sample from Wind dataset, we found that there exists a significant positive relationship between excess return of a stock and incremental proportion of discussion on a particular stock. We conjecture that this effect on stock returns is due to the change in public attention. This characteristic is helpful when investors want to hedge or generate excess return under extreme market condition.