Abstract: In order to prevent the gob gas explosion, taking 17 major and particular major underground mine accidents which happened in gob since 2000 for samples. Using accidents statistic analysis method, we study the causes which cause unsafe action. The results showed that the total of 27 types of unsafe acts can be summarized to 7 groups such as blasting in violation, managing stopping in violation, managing gob in violation; front-line workers (containing blasting in violation, managing sealing in violation and entering the off-limits) and high level managers (containing managing sealing in violation, crossing the line or ultra ability mining, illegal command and goaf management) have more unsafe acts.