5 kinds of diamond drilling bits were prepared with different matrix hardness and profiles by hot pressing sintering method, which were tested in engineering exploration and compared with the common electroplated diamond drilling bits to analyze the drilling efficiency. The result shows that by optimized design, the hot pressing sintering diamond bits are suitable for engineering exploration equally, their drilling efficiency are almost equal to or even higher than that of the electroplated diamond drilling bits. In weathered limestone formation drilling, the lower the matrix hardness of hot pressing sintering bit, the higher the drilling efficiency, and vice versa. The profile of bit by special teeth design is faster exposed than that by plain teeth design with higher drilling efficiency.