Cephem compounds, its pharmaceutically acceptable salt and its application method, wherein the compound has bicyclic nitrogenous heteroaromatic as 3 quaternary ammonium methyl, with one of the following or two: being connected to the end amidine residue (substituted or unsubstituted) of aryl or 5- or 6- units heteroaryls (substituted or unsubstituted), the aryl or 5- or 6- units heteroaryls (substituted or unsubstituted) are also connected to the bicyclic free N atoms containing quaternary nitrogen on 3- side chains by spacer group Or it is connected to the end guanidine residue of aryl or 5- or 6- units heteroaryls (substituted or unsubstituted), the aryl or 5- or 6- units heteroaryls (substituted or unsubstituted) are also connected to the bicyclic free N atoms containing quaternary nitrogen on 3- side chains by spacer group.
