An improved oil injector oil return pipeline of a diesel locomotive diesel engine belongs to the technical field of diesel locomotive diesel engine equipment and aims at reducing circulation resistance of a right side oil injector during the oil return process and achieving the aim of oil saving, fire prevention and environment protection. The technical scheme is that a right side oil return pipeline hole is drilled on a vehicle body on the lower portion of a main generator, a right side oil return pipe of a diesel engine penetrates through the right side oil return pipeline hole and is directly connected with an oil return main pipe at the root portion of a fuel tank at the bottom of the main generator to enter the fuel tank. The improved oil injector oil return pipeline of the diesel locomotive diesel engine has the advantages of greatly reducing dirt oil stock of a dirt oil pool, fundamentally avoiding oil dripping and oil leakage at connector positions of the oil return pipeline, avoiding oil pollution caused by waste oil spilled onto a traction motor, facilitating maintenance and fire prevention of the motor, avoiding environment pollution caused by waste oil spilled on two sides of a railway line, avoiding waste caused by the fact that a large amount of fuel flows into a dirt oil tank and facilitating saving.