A strain relieving element, comprising: a front surface, a rear surface opposite to the front surface, an intermediate portion connecting the front surface to the rear surface, a receiving passage passing through the front surface and the rear surface, two rows of through cavities extending inwardly from the intermediate portion at least, a rib dividing the adjacent through cavities in same row and a convex respectively formed between the adjacent rows of the through cavities, and between the adjacent rows of the ribs. The rib near to the rear surface is bigger than the rib far from the rear surface, the width of the ribs are gradually decreased along an axis direction from the rear surface to the front surface.