An electromagnetic-pneumatic combination weft insertion mechanism comprises a main jet weft-inserting device, a weft cut-off device, an airflow passage component, a weft detection sensor, a microprocessor and an auxiliary nozzle. The airflow passage component is composed of extensible electromagnetic-pneumatic integrated weft-inserters; one side of each extensible electromagnetic-pneumatic integrated weft-inserter is provided with an electromagnetic coil, while an electromagnetic disc composed of an extensible electromagnetic disc plastic layer and an electromagnetic disc magnet layer is pasted to the other side; the length of a required weft insertion passageway is determined flexibly according to fabric breadth. During operating processes, when detecting a weft, the weft detection sensornear a main nozzle provides feedback to the microprocessor; the microprocessor controls positive and reverse connections of electromagnetic coil circuits on the weft-inserters so that the adjacent weft-inserter electromagnetic discs perform sucking or rebounding under the action of an electromagnetic field, and a weft insertion passage is closed and reset. A novel weft insertion mode having a nearly-enclosed flight cavity is provided herein; the whole weft insertion process is more efficient and more energy efficient at the premise of weaving broad cloths.