Nitrogen doped carbon dots were synthesized using the hydrothermal reaction of cellulose and urea, and then carbonized in a N2 atmosphere at a high temperature to prepare N-doped carbon dots decorated with manganese oxide nanospheres (N-CMOS) formed using cetyltrimethylammonium bromide (CTAB) and MnO. The introduction of N-CMOS resulted in a large specific surface area, abundant pores, favourable conductivity and an excellent electrocatalytic performance. A glassy carbon electrode modified with N-CMOS was used for the simultaneous identification of paracetamol (AP) and p-aminophenol (PAP) utilising differential pulse voltammetry. Under optimum conditions, the electrical sensor showed a wide linear range of 0.1-100 μM for PAP and 0.1-80 μM for AP, with detection limits of 0.0456 and 0.0303 μM (S/N = 3), respectively. The sensitivities for detecting PAP and AP were calculated as 1.615 and 1.971 μA μM-1 cm-2, respectively. The sensitivity and limit of detection (LOD) meet the requirements of detection of drug impurity limits in tablets. In addition, the sensor has been successfully applied to detect PAP and AP in paracetamol tablets. The constructed sensor not only possesses a superior repeatability, reproducibility and stability, but a relatively wide linear range, and a superior detection limit and sensitivity.