Abstract: The rotational interia about a fixed axis for body with fractal form is discussed. The figure enclosed by the Koch snowflake curve is used as an example, the iteration alogrithm and the formula are given for the figure＇s rotational interia about a horizontal fixed axis through the centroid. The obtained result is in agreement with the accurate result. The presented method has normalized steps, and it is convinent for programming. The proposed method can also be applied to the extension of other fractal figures.

Key words: fractal, iteration, rotational interia