A method of fabricating the multi-layer subwavelength circular gratings is proposed, which is based on the high-order waveguide mode interference and continuous sample rotation. The waveguide mode interference field is simulated by the finite element method, and the coordinate rotation matrix and the numerical simulation method are used to study the total optical field after performing continuous rotating exposure to the sample. A 442-nm laser is selected as the excitation light and TE₅ and TM₅₁ are taken as the examples to study the optical field distribution of the multi-layer subwavelength circular gratings fabricated by the high-order waveguide mode interference. By the optical filed distribution, the period of the X-Y plane and the period and layers of the Z-axis of the multi-layer subwavelength circular gratings are analyzed, which can be adjusted by changing the thicknesses of the photoresists and the waveguide modes for interference exposure. Under the condition of the same thickness of photoresist, there are many high-order waveguide modes and the excitation angle corresponding to the same high-order waveguide mode can be effectively controlled by changing the thicknesses of photoresists. As a result, the multi-layer circular gratings with different parameters can be fabricated by selecting the photoresists of different thicknesses and the high-order waveguide modes used in exposure. The proposed method is a simple and effective way to fabricate the multi-layer subwavelength circular gratings and has a certain application prospect in the field of micro-nano optics.