For developing domestic LWD tools with boundary detection capability, taking Schlumberger’s boundary detection instrument PeriScope as example, the functions of orientational electromagnetic wave resistivity is introduced, together with the influence elements of boundary detection and the advantages of PeriScope over conventional LWD. The boundary detection model built has described the working mode and then the basic theory of PeriScope. Through the horizontal well drilling at MaHu area in Xinjiang oilfield, the application results of PeriScopeis analyzed. And 2 suggestions for domestic development of boundary detection instrument are put out. 1 . refer to the principle of rotary steering to achieve the 360° electromagnetic waves ending /receiving while the drill tool rotating; 2, to detect the boundaries directly above or below the tool while drill string not rotating.