Working method of outer pipeline crawling robot

The invention discloses a working method of an outer pipeline crawling robot, the outer pipeline crawling robot is applied, the outer pipeline crawling robot is characterized in that three layers of annular bases are sequentially arranged in the longitudinal direction, each layer of annular base is arranged on the periphery of a pipeline in a sleeving mode through a through hole formed in the center, and every two adjacent layers of annular bases are connected through a lifting telescopic cylinder arranged in the longitudinal direction; according to the method, the corresponding lifting telescopic cylinders are made to stretch or retract, and when one layer of annular base moves in the preset direction, the other two layers of annular bases hold the outer wall of the pipeline through the holding assemblies on the annular bases; and the three layers of annular bases alternately and sequentially move in the preset direction, and the steps are repeated, so that continuous wriggling and climbing along the outer w