The invention discloses an optical anti-counterfeiting element and a manufacturing method thereof. The method comprises the steps that a fluctuating structural layer (2) is formed on a base material (1), and the fluctuating structural layer (2) at least comprises a first area and a second area, wherein the first area is of a first fluctuating structure, and the second area is adjacent to the first area and is of a second fluctuating structure; the second fluctuating structure is provided with a side wall, wherein the included angle formed between the plane of the base material (1) and the side wall is larger than 45 degrees, and the depth-to-width ratio of the second fluctuating structure is smaller than 0.3; a clad layer (3) is formed on the fluctuating structural layer (2); and the clad layer (3) is arranged in the clad layer removal environment till the clad layer (3) on the second area is stripped from the fluctuating structural layer (2).