A new ligand N,N′ bis[(1 phenyl 3 methyl 5 oxo 4 pyrazolinyl) 2 thenoylmethylidyne]ethyl enediimine (HPMTHP)\-2en and its five complexes have been sythesized. These complexes have the general formula [M(PMTHP)\-2en], where M=Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ), Pd(Ⅱ), Pt(Ⅱ). They were characterized by elemental analysis, IR, UV vis, magnetic moments and molar conductance. The results showed that the complexes are all of quadricoordinate square planar geometry. The antibacterial experiment indicated that they have high antibacterial activities against S. aureus, B. subtillis, E. coli, E. carotovora, C. flaccumfaciens.