A rail-type organic light emitting diode lamp assembly is provided. The lamp assembly includes a lamp module, an annular member, a connector, a conductive member, and a rail module. The annular member includes a protrusion portion having a pair of indentations. The connector is connected to the annular member, and includes a through hole, a first end provided with a pair of ears and a second end provided with a pair of hooks. The conductive member is provided in the through hole and has a first end in contact with the annular conductive coil. The rail module is connected with the connector and includes a conductor in contact with a second end of the conductive member. The connector can be slidably hooked to the rail module through the hooks, and after the ears are inserted into the indentations, the annular member can be rotatable with respect to the connector.