Research conclusions:(1)The integral dropper with current carrying capacity should have the significant function distributing current with parallel many points，only the three-five droppers and one electrical connector near the current change point could take part in the current distribution of OCS，and the other droppers and the electrical connectors should hardly take part in the current distribution which currents should approach zero.(2)Because the cross section of the dropper is limited，the dropper at the continuous current change point cannot undertake the current flowing, where the electrical connector must be set.(3)The electrical connectors should be set as a practical setting principles at the connection joints among the power supply lines and OCS，insulated overlaps，non-insulated overlaps， the connection joints among OCSs of differential rail tracks, and the electrical connectors need not be set at the other parts of OCS. The principles should be applied to all types of the OCS in electric railways.