Abstract: This paper presents an investigation of the“Automatic Operator”of Diesel Loco- motive based on the principle of compound programming control.According to the sur- rounding conditions of locomotive,the“Automatic Operator”can change its structure automatically in order to obtain better quality of control. In this paper,the principle scheme,the characteristics of“Automatic Operator”and the experimental results of automatic control of Diesel locomotive with“Automatic Operator”are presented,the principle and the design of logical circuit for changing the characteristics of“Automatic Operator”is emphasized.The latter part of the paper in- cludes a discussion of quality of control;and finally,formulas for determining the para- meters of the control system are derived.