A random branched poly(hydroxyetheramine) was synthesized by ring-opening reaction of tetraethylenepentamine (TEPA) to ethylenediglycidol (EG), which was denoted as PTEG. PTEG has not only high charge density but also discrete charge distribution due to the introduction of hydrophilic hydroxyoligoether. In addition, PTEG contains all grades of protonable amines. Acid base titration indicated that PTEG was protonated in wide pH range from 5.0 to 11.0, which showed that PTEG had proton sponge effect as polyethylenimine and protonation ability at human physiological pH condition. In dilute aqueous solution, PTEG was complexed with weak anionic polymer, poly(acrylic acid) (PAA), into nanoparticles.