In view of the prominent problem of high root rate in deep hole bench blasting in Jilangde coal mine, it is considered that the method of adjusting the ultra-depth of the borehole can be adopted to solve this problem through field investigation. Therefore, the reasonable range of borehole depth is firstly obtained based on the current commonly used calculation methods and theoretical calculation of borehole depth. In view of the main reason for the high root rate is serious overbreak, it is proposed to reduce the ultra-depth of the borehole from 1m to 0.8m. Then, tests are firstly carried out on 1380 and 1392 platforms. GPS is adopted to measure the elevation of the test platform and 3D elevation map is drawn to evaluate the root rate. It is found that the improved blasting scheme achieves good effect, which not only effectively reduces the root rate, but also reduces the explosive consumption and drilling workload. Finally, many repeated tests are also carried out, which shows that 85% of these achieve good blasting effect. But for some low elevation platform, such as the southwest platform1284, its blasting effect is not very ideal. It may be assumed that the rock integrity and strength increases and then the clamping force at the bottom of the borehole strengthens with the reduction of the platform elevation, and therefore the ultra-depth of the borehole should be increased.