A joint assembly for a truss bottom plate, the truss bottom plate includes a first bottom plate and a second bottom plate adjacent to each other, and a gap exists at an adjacent position between the first bottom plate and the second bottom plate; the joint assembly includes a first barrier plate and a second barrier plate; the first barrier plate is connected with the first bottom plate; the second barrier plate is connected with the second bottom plate; a part of the first barrier plate is arranged to overlap a part of the second barrier plate and cover the gap. A truss of an escalator or a passenger conveyor, the truss of the escalator or the passenger conveyor includes the joint assembly as described above.