Mileage measuring mechanism for inner detection of pipeline

The invention relates to a mileage measuring mechanism for inner detection of a pipeline, and applies to the field of millage measuring and positioning for inner detection of an oil gas pipeline. The mechanism is that a mileage wheel I and a mileage wheel II are respectively mounted at two ends of a floating arm; the floating arm, a rotating arm and a spring form a triangular structure; the mileage wheel I and the mileage II are clung to the pipe wall all the time under the tension effect of the spring. The mechanism has the characteristics of being simple in structure and small in space used; the capacity of the mechanism passing through the pipeline is improved; in addition, the diameter of the mileage wheels can be relatively increased; a rotating force arm is enlarged, thus the slipping can be avoided, and as a result, the mileage measurement accuracy can be improved.