Abstract: This paper introduces the basic principle of microseism CT inversion and three CT evaluation indicators firstly, and then analyses the correlation between the three CT evaluation indicators and electromagnetic radiation strength with the result of microseism CT inversion and the monitoring electromagnetic radiation data in field, determining the apparent relationship existing in them. Furthermore, three principal components corresponding to the three CT evaluation indicators are calculated by principal component analysis method, and with the contribution rate value of different principal component, it is determined that the first principal component Y1 can replace the three single CT evaluation indicator effectively. Finally, the first principal component Y1 was used to re-evaluate the impact of risk on the work face and finds a new 2# danger area, indicating that the new comprehensive evaluation indicator Y1 is more general and reliable and has a great significance to the risk evaluation of rock burst.