The invention discloses a judging method for a rock burst risk area during excavating a lower step of a deep large cross-section tunnel. The judging method for the rock burst risk area during excavating the lower step of the deep large cross-section tunnel includes the following steps: A, performing micro-seismic monitoring research during excavating an upper step of the deep large cross-section tunnel to pre-judge a rock burst risk area during excavating the lower step; B, analyzing the hard structure surface, fracture group number, oblique angle and combination relation generated by excavating the area and the angle between the area and the axial line of the tunnel for the step A; C, analyzing the support intensity and effect of an upper section of the tunnel for the step A; D, pre-judging the burst risk generated in excavating the lower step for the step A according to tunneling speed rate and excavated step height; E, pre-judging the rock burst risk area generated in excavating the lower step of the deep large cross-section tunnel for the step A; F, judging the rock burst risk area generated in excavating the lower step of the deep large cross-section tunnel for the steps A, B, C, D and E. The judging method for the rock burst risk area during excavating the lower step of the deep large cross-section tunnel lowers or avoids the rock burst risk during excavating the lower step of the deep large cross-section tunnel and enables the constructor safety and the engineering construction progress to be guaranteed.