In the present work, unzipped multiwalled carbon nanotube oxides (UMCNOs) was obtained from longitudinally unzipped multiwalled carbon nanotubes (MWCNTs) by the Hummers method. This hybrid structure could significantly improve the accessible area since both the outer and inner wall of MWCNTs are available. Then a novel strategy based on overoxidized poly(p-aminophenol) (pAPox) and UMCNOs copolymer modified electrode was proposed for the simultaneous determination of dopamine (DA), uric acid (UA), and tryptophan (Trp). Besides, the coexistence of ascorbic acid (AA) has no interference toward the detection of DA, UA and Trp. Also, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), cyclic voltammetry (CV) and different pulse voltammetry (DPV) were employed to characterize the copolymer. Under the optimal conditions, two linear calibrations for DA and Trp were obtained over ranges of 15.0-95.0 mu M, 115.0-515.0 mu M and 5.0-185.0 mu M, 265.0-1265.0 mu M respectively with detection limit (S/N = 3) of 0.33 mu M and 0.47 mu M. Three linear calibrations for UA were obtained over ranges of 7.0-57.0 mu M, 87.0-582.0 mu M and 752.0-2402.0 mu M with detection limit (S/N = 3) of 0.40 mu M. In addition, satisfactory results were obtained using the modified electrode to detect DA, UA and Trp in samples via standard addition method.