The utility model relates to the field of automobiles, in particular to a seat armrest storage mechanism which comprises a storage shell and a storage frame, the storage frame slides in the storage shell in a limited mode, and the storage frame comprises a storage drawer, a storage bottom plate, a storage upper side plate, a storage lower side plate and a storage side baffle. The storage upper side plates and the storage side baffles are movably hinged to the corresponding inner side walls of the storage drawer respectively, the two storage upper side plates and the two storage side baffles are arranged on the different inner side walls in the storage drawer respectively, the lower ends of the storage upper side plates are movably hinged to the upper ends of the storage lower side plates, and the storage bottom plate is arranged between the two storage lower side plates. The two opposite end faces of the storage bottom plate are movably hinged to the corresponding storage lower side plates respectively. By designing the foldable storage frame, the purpose of expanding the storage space of the rear row can be achieved, the use state of the storage mechanism can be flexibly adjusted according to different requirements, the overall structure is simple and stable, operation is easy, and different use scenes can be met.