In this work, pomelo peel was used as crude material, ammonia, sodium hydroxide and potassium hydroxide was used as activators, then a class of biochar materials were prepared by one-step pyrolysis. The structure and morphology of these materials were characterized by SEM, XRD, and Fully automated surface analyzer; then, the Electrochemical ac impedance technique (EIS) and Cyclic voltammetry (CV) were used to test their electrochemical properties. Compared to other materials, Pyrolytic carbon produced by activation of potassium hydroxide possessed the most abundant pore distribution, while showed the most superior electrochemical properties. This kind of carbon material was modified on the surface of glassy carbon electrode(GCE) by cast. The electrochemical behavior of hydroquinone (HQ) and catechol (CA) at different electrodes were investigated by differential pulse voltammetry (DPV) in PBS solution (pH=7.0). The results indicated that compared to other electrodes, the PC-4/GCE was the most superior to HQ and CA at the same time. Under optimal conditions, when the concentration of HQ and CA were in the range of 0.5~100 μmol/L, a good linear relationship between the PC-4/GCE response current and its concentration has been showed, the detection limits were 0.023μmol/L and 0.040μmol/L, respectively. Meanwhile, the sensor had good stability, and its relative standard deviation values (RSD) were 2.3% and 3.5%, respectively. HQ and CA in tap water samples were detected by standard recovery, and add standard recovery range was 97.8~101.7.