The invention discloses a robot walking outside a pipeline, which consists of a power driving device, a walking guide device and an elastic element assembly (11) connected with the walking guide device. The power driving device is a rotary body consisting of a cylindrical body (1) and a cylindrical driving main body (4) through a rolling bearing (3), the inner wall of the cylindrical body (1) is fixedly provided with more than one motor (2), and a motor shaft is parallel to the axis of the cylindrical body (1) and is provided with a gear (6); one end of the inner wall of the cylindrical driving main body (4) is fixedly provided with an annular gear (5) which is engaged with the gear (6), the inner wall of the cylindrical driving main body (4) is provided with a group of driving wheels (8), and the rotating axes of the driving wheels (8) and the cylindrical driving main body (4) form an acute angle; and the inner wall of a cylindrical guide main body (12) of the walking guide device is provided with at least more than two groups of guide wheels (14), and the rotating axes of the guide wheels (14) are mutually vertical to the axis of the cylindrical guide main body (12). Both a mounting frame (7) and a guide wheel carrier (13) are floating bodies, and an elastic element (15) is used for producing a certain radial expansion amount so that the driving wheels (8) and the guide wheels (14) are attached to the outer wall of the pipeline (10) all the time. After the driving of the motor, the motor can advance or retract along the axis direction of the pipeline, and can be used for operations such as outer pipe quality detection, maintenance, repair and the like of various pipelines and stayed bridge cables.