Carbonized La-Mo cathode applied in FU105 large powerful broadcast emission tube has been studied. Referred to carbonized Th-W cathode , the carbonizing techniques of La-Mo cathode was worked out. Exhausting and seasoning of carbonized La-Mo cathode for FU105 tube were carried out. Through the performance test of FU105 tube equipped with La-Mo cathode, the emission capacity and stabilization of carbonized La-Mo cathode were analyzed. The results show that the emission capacity of carbonized La-Mo cathode for FU105 tube has reached that of Th-W cathode, but its emission stabilization is not very good.