Abstract: Coal-rock interface detection principle using ground penetrating radar was introduced. Feasibility and practicability of using ground penetrating radar technology to detect coal-rock interface was discussed. The radar antenna with frequency of 200 MHz-1 GHz was proved to realize most of coal-rock interface detection through theoretical analysis. The experiment was taken by use of LTD-2100 ground penetrating radar in Guozhuang Coal Mine. The experimental results show that radar antenna with frequency of 400 MHz can realize detection of gas coal-sandstone interface with a small error.