In order to ensure the stability of the surrounding rock of underground mining excavation tunnels and identify unfavorable geological bodies ahead, geological radar was used to detect the empty area of the surrounding rock and floor of the excavation tunnel, and stability analysis was conducted on the surrounding rock of the tunnel under different geostress effects. The axial force of anchor rods with different lengths of reinforcement was compared. The results indicate that both areas detect by the radar exhibit strong amplitude reflection zones at different depths. Under the action of 1.5 m anchor rod support, the maximum displacement of the surrounding rock decreases by 39.3% and 10.0% respectively, and the X-effective stress increases by 42.8% and 37.5% respectively. The axial force changes are basically the same when supported by 1.5 m and 1.8 m anchor rods. Based on the continuity of the same phase axis, the abnormal area is judged, and the abnormal signal is the unfilled area and cavity, which are supported by anchor bolts, anchor mesh, and shotcrete. The research results can provide reference significance for the stability and support of surrounding rocks in similar mine tunnels.