Disclosed are an interline nondestructive single-phase diverter and a design method and a control method thereof. The diverter comprises an on-load tap-changer, a diverter transformer, a voltage dividing transformer, a control motor, a microprocessor, two selector switches and a temperature sensing unit. The diverter is mounted between two guide lines. An input end of the diverter is connected with inner conductors and a first selector switch close to electricity load, and an output end of the diverter is connected with inner conductors, outer conductors and a second selector switch close to asupply end power source in the next section. The diverter transformer and the voltage dividing transformer are boosting transformers, and according to differences in structures, the diverter transformer is a duplex-winding diverter transformer or a self-coupling diverter transformer, and the voltage dividing transformer is a duplex-winding voltage dividing transformer or a self-coupling voltage dividing transformer. By means of calculating a coil turn ratio of the transformers, the selector switches are controlled by the microprocessor to enable current of the conductors to exactly meet requirement on ice resisting and melting, and the current and ice resisting and melting can be controlled precisely. The interline nondestructive single-phase diverter can work under a normal power transmission mode and an ice resisting and melting mode, and is simple and reliable to operate.