It is reported ruthenium complexes show no photoluminescence in aqueous solution at ambient temperature, but display intense photoluminescence in The presence of double- helical DNA,to which The complex bind avoidly. These characteristics may become particularly useful in developing new diagnostic reagent based upon luminescent DNA probes. So, There has been increasing attention given to The design of ruthenium complexes and Their photoluminescence characteristics. But there is no report on mass spectromotric study of These complexes. In this paper, The fast atom bombardment mass spectra of newly synthesized ruthenium complex Ru(bpy)_2(dppx) (BF_4)_ 2 (bpy=2, 2’bipyridine, dppx=dipyrido<3,2, -a-2’, 3’-c>phenaxylene)was discussed. A ccording to The fragment ions and related knowledge, The molecule structure is characterized. These will provide some valuable references to synthesize These complexes and characterize Their molecule Structures.