The invention provides a connecting plug-in unit of a wire harness with reliable and fast connection, the connecting plug-in unit of the wire harness comprises a vehicle body plug-in unit and a battery pack plug-in unit, wherein the vehicle body plug-in unit comprises a vehicle body connecting base and a vehicle body connecting plug-in unit, the vehicle body connecting base and the vehicle body connecting plug-in unit are provided with corresponding connecting holes, the vehicle body connecting base and the vehicle body connecting plug-in unit are connected by utilizing a bolt penetrating the connecting holes, the diameter of a bolt body of the bolt is smaller than that of the connecting holes, the diameter of a bolt cap and the diameter of a nut matched with the bolt are larger than that of the connecting holes, a spring is sheathed on the bolt, and two ends of the spring respectively butt against the vehicle body connecting base and the vehicle body connecting plug-in unit; the vehicle body connecting plug-in unit is provided with a connecting terminal and a positioning pin hole in the consistent direction with the spring; and the battery pack plug-in unit is provided with the connecting terminal and a positioning pin which are respectively matched with the connecting terminal and the positioning pin hole of the vehicle body connecting plug-in unit. The connecting plug-in unit of the wire harness has simple structure and reliable connection, and can reduce the number of the connecting plug-in units of the wire harness and further save the cost and the time for disassembling and assembling a battery pack.