The invention discloses a beam length variable simply supported beam and continuous beam self-vibration characteristic test platform, which comprises a sliding support, a limiting support, a movable base, a fixed base, a foundation platform, an acceleration sensor, a computer, a dynamic signal testing and analyzing system and a force hammer sensor, and is characterized in that the movable base and the sliding support can be adjusted and fixed according to the span of a test beam, a rolling bearing can be moved along a sliding rail, and fine adjustment is carried out on the distance between the sliding support and the limiting support; after the distance between the sliding support and the limiting support is determined, and limiting boards are placed at a gap between the bearing and the sliding rail so as to limit and fix the bearing. The test beam is placed on the sliding support and the limiting support; the sliding support and the limiting support are respectively fixed with support ends of the test beam through hook bolts and a double-hole clamping plate; the acceleration sensor is arranged on a test point at the surface of the test beam, and the acceleration sensor and the force hammer sensor are connected to the dynamic signal testing and analyzing system and are electrically connected with the computer; and a dynamic load is applied through the force hammer sensor, and thus a self-vibration characteristic test can be performed. Through movement of the movable base or increasing the number of the movable base, a test for self-vibration characteristics of simply supported beams or continuous beams with different beam lengths and spans can be realized, and the universality and the accuracy of the test platform are reflected.