The invention discloses a motor vehicle rapid on-duty driving and off-duty driving method circuit of a centralized power rail motor unit. The motor vehicle rapid on-duty driving and off-duty driving method circuit of the centralized power rail motor unit comprises two motor vehicles of the same circuit structure, the two motor vehicles are connected with each other through a power supply through wire and a power off through wire, the power source of each motor vehicle is divided into four channels after being led out positively: the first channel is connected to a contact 4 and a contact 3 of a rapid on-duty driving / off-duty driving shift switch SA10, the first channel is connected with a relay coil KEX after being led out from the contact 3, and then connected to a power source cathode; the second channel is connected to a contact 6 and a contact 5 of the rapid on-duty driving / off-duty driving change-over switch SA10, and the second channel is connected to an output end of a contactor normally open auxiliary contact KMF and the power supply through wire after being led out from the contact 5; the third channel is connected to the power source cathode after being connected with a relay normally close contact KE, a parallel circuit of the contactor normally open auxiliary contact KMF and a contactor coil KMX sequentially; and the fourth channel is connected to a motor vehicle load after being connected with a direct current contactor main contact KM. By adopting the method circuit, the operability of the motor vehicle in the centralized power rail motor unit is enhanced, the workload of crews is reduced, and the working efficiency is improved.