A new hyperbranched polymer was prepared by the one-pot Knoevenagel polycondensation of 4-[N,N-bis(hydroxyethyl)amino-4'-formyl]-azobenzene (CHO-DOH) with cyanoacetic acid using 4-(dimethylamino)pyridine (DMAP) as a base in tetrahydrofuran (THF). This polymer was soluble in polar aprotic solvents such as N,N-dimethylformamide and dimethyl sulfoxide, The glass transition temperature (T-g) of the polymer was observed at 145 degreesC for PE-Azo/Hyper. The second harmonic generation (SHG) measurements of the obtained polymer were carried out by the Maker fringe method after corona poling at 7 kV near T-g for 10 minutes. The second-order nonlinear optical coefficient, d(33) was about 15 pm/V for PE-Azo/Hyper.