The invention relates to the technical field of pipeline detection, and particularly relates to an experimental platform of a pipeline magnetic flux leakage detection theory. The experimental platform of the pipeline magnetic flux leakage detection theory comprises a bracket, a driving device, a travelling crane device and a magnetic flux leakage detection module, wherein the travelling crane device is driven to move along the bracket by the driving device, and the moving speed of the travelling crane device under the driving of the driving device can be adjusted; the magnetic flux leakage detection module is arranged on the travelling crane device, and the position of the magnetic flux leakage detection module relative to the travelling crane device can be adjusted; a to-be-tested piece placing space is formed on the bracket and below a moving area of the travelling crane device. According to the testing platform provided by the invention, the running speed and position of the travelling crane device can be precisely controlled, magnetic flux leakage signals are collected by the magnetic flux leakage detection module which is arranged on the travelling crane device, and collected data are used for analyzing and researching the relation between leakage magnetic field signals and defect sizes and assisting the development of an in-pipeline magnetic flux leakage detector.