The invention relates to a power supply system of a sliding contact line of a trench of a tyre crane of a container yard, which comprises a trench cell body and a trench cover plate covered and arranged at an opening part of the trench cell body, the sliding contact line is arranged in the trench cell body along the extension direction of the cell body, a track is arranged by being parallel to the sliding contact line, a current-collecting trolley is movably arranged on the track, an electricity getting device of the current-collecting trolley is in sliding elastic contact with the sliding contact line, a gap is arranged between the trench cover plate and the trench cell body or in the trench cover plate for leading the current-collecting trolley to lead out a conductive wire, a flexible or rigid movable cover can be added at the gap according to the needs, the corresponding current-collecting trolley has the automatic cover-turning function when travelling, and a traction conductive wire is respectively connected with the current-collecting trolley and the tyre crane. The adoption of the power supply system can lead the tyre crane to span a container region in a linear non-interruption manner in the container yard; compared with the existing scheme, the power supply has the advantages of simplicity, practicality, low cost, small occupied space, safety, reliability and a wide range of applications, thereby being an effective complementary way or an effective alternative way of the prior art.