Disclosed are connectors and collapsible bed frames. A collapsible bed frame includes lateral and longitudinal bar units. Between each of two adjacent lateral bar units, a first longitudinal bar unit is disposed at a first side of the collapsible bed frame and a second longitudinal bar unit is disposed at a second side of the collapsible bed frame. The first and second longitudinal bar units and the two adjacent lateral bar units are rotatably connected with each other by connectors that enable the collapsible bed frame to contract and expand while the lateral and longitudinal bar units are connected with each other.