Polyamidoamine-phenyl aldehyde of G3.0 and G4.0 dendrimers were prepared with ethylenediamine as center core, methyl acrylate as branch monomer and phenyl aldehyde as terminated functional group by divergent method. The fluorescent property of polyamidoamine-phenyl aldehyde dendrimer was studied. The results showed that fluorescence of the different generation polyamidoamine-phenyl aldehyde dendrimer was all quenched by Fe3+ in the solution and a red shift of the fluorescent emission peak was observed also. The fluorescence of polyamidoamine-phenyl aldehyde dendrimer was increased by Zn2+ in the solution. But, the fluorescence of polyamidoamine-phenyl aldehyde dendrimer decreased when the mole ratio of Zn2+/dendrimer continuously increased.