Dihydroxybenzenes, including hydroquinone (HQ), catechol (CC) and resorcinol (RS), are important environmental pollutants that poses a serious threat to human health at high concentrations. Accurately and rapidly detecting dihydroxyphenyl groups in actual samples is of great significance for environmental monitoring and protection. Electrochemical sensors, as a fast and convenient analytical tool, have long had bottlenecks such as poor specificity. Here, an electrochemical sensor has been developed with nitrogen-doped Mo₂C/C nanocomposites as the sensing catalyst for simultaneous detection of HQ, CC and RS. The oxidation peak potentials of HQ, CC and RS on MoC/C/GCE were -0.05 V, 0.16 V and 0.50 V (vs. Ag/AgCl) respectively, indicating that the electrochemical oxidation processes of the three dihydroxyphenyl isomers were independent and do not interfere with each other. The responses to HQ, CC, and RS exhibit linear relationships within the ranges 0.5 ~ 1000 μM, 1.0 ~ 1000 μM and 2.0 ~ 900 μM, respectively. The corresponding detection limits are 0.13, 0.15 and 0.85 μM (S/N = 3), respectively. Moreover, MoC/C/GCE exhibits excellent anti-interference, repeatability, reproducibility, and stability in the simultaneous detection of HQ, CC, and RS, providing clear evidence for the application of MoC/C/GCE in analysis of actual water samples.