At present,the work of loading and unloading drill pipe for all kinds of engineering drillers in drilling process is almost done by workers in our country.By this way the efficiency is not only low but also there is very serious hidden trouble to the manipulators.In this paper,a design scheme to achieve the function of automatically replacing drill pipe for engineering drillers is brought forward,the machine structure and hydraulic system of drill pipe automatically-replacing device and its working procedures introduced in detail.It can schlep six drill pipes at the same time,which achieves automatic replacing of pipe by the manipulator driven by the hydraulic system,and has high efficiency and security.