As the important device, self-loading device plays a key role in the side-crane used for container. And as the key component of the self-loading device, loading arm’s strength analysis is very important. FEA is introduced into the arm’s strength and rigidity analysis, and under the precondition of satisfying allowable stress, minimum weight of the arm is taken as the design target. Ulteriorly, by obtaining optimal geometric parameters, the loading arm’s optimization design can be realized and its manufacture cost can be reduced.