The invention provides an obstacle-crossing robot for transmission line operation and an obstacle-crossing method thereof. The robot comprises a body, a front swinging arm, a rear swinging arm, a front roller wheel, a rear roller wheel, a front arm slider, a rear arm slider and an auxiliary arm. The method comprises the following steps: when a sense director of the robot detects that obstacles exist, the robot first loosens conductors in wheel-type hands of the two front arms, and then swings the two arms outward, moves round the obstacles by 180 degrees of rotation and grips the conductors again, at the moment, the robot crosses the obstacles. The two rear arms adopt the same method to cross the obstacles. After crossing the obstacles, the robot reverses the four arms to prepare for the next obstacle-crossing. The robot is suitable for the signal conductor and bundled conductor, and can complete multiple operations. The method features clear and simple steps. All the driving motors are all in sequential working state, without multi-motor linkage. The robot is characterized by considerably easy control system manufacturing and programming, thus having good adaptability to the field.