Abstract: A NiTi alloy root canal file with a flexibility gradient includes a tip segment (F1), a middle segment (F2) and a root segment (F3) divided along the axis of the NiTi alloy root canal file with the flexibility gradient. The internal microstructure of the tip segment (F1) of the root canal file is martensite M-phase, the internal microstructure of the middle segment (F2) is R-phase, and the internal microstructure of the root segment (F3) is austenite A-Phase. The present invention further provides a manufacturing method for the NiTi alloy root canal file with the flexibility gradient. The beneficial effect of the present invention is effectively improving safety in use.