A bi-directional positioning sliding rail assembly includes a sliding rail set including an outer rail and an inner rail linearly slidably coupled together, an actuator mounted in the inner rail and providing a push member having opposing first push end and second push end, and a position-limiting mechanism mounted in the inner rail and including a first position-limiting member and a second position-limiting member that are pivotally connected to the inner rail and respectively disposed adjacent to the first push end and second push end of the push member and alternatively biasable relative to the inner rail by the actuator. Thus, the bi-directional positioning sliding rail assembly has the advantages of simple structure and ease of fabrication and use.