Abstract: Geometrical construction analysis is an essential and fundamental topic in structural mechanics. In general, geometrical construction analysis is conducted using three basic geometrical construction rules and some auxiliary rules. Considering that directional support (or double-link support) is a common support in structural mechanics, four auxiliary rules related to directional support are proposed in this paper. With the assistance of these four auxiliary rules, the geometric construction analysis process of many structures with directional supports becomes clear and simple. Five examples are given to prove that the four auxiliary rules for directional support are easy to understand and effective.