The invention relates to a completing tool for horizontal wells and large displacement wells, particularly to a guiding tool with a drifting function for downwards running a casing pipe capable of being fished. A casing pipe buckle is designed at the upper end of a casing of the device; the inner wall of the casing is connected with a thrust gland through fixing pins; the lower end surface of the thrust gland is propped against the step of the inner wall of the casing; the thrust gland sleeves a casing of a turbine set; a fishing sleeve is arranged on the outer side of the upper end of the casing of the turbine set; an axial limiting bearing sleeves the lower middle axle of the turbine set; the lower end of the middle axle of the turbine set is connected with a rotary guiding shoe; a scraping belt is arranged on the surface of the rotary guiding shoe. According to the invention, when the casing pipe is downwards placed and encounters a well resisting section, the casing pipe can drive the rotary guiding shoe to rotate at a high speed, thereby having the better drifting function, reducing the downward running difficulty of a casing pipe string and reducing danger; when the casing pipe string is downwards placed to the place of the expected well depth, the tool body can be fished out of the casing pipe without affecting the follow-up construction after well drilling; the defect that the casing pipe at part of the well section of the conventional horizontal wells, directional wells and large displacement wells cannot be downwards placed smoothly is overcome.