N-doped porous biochar (NPB) with large conjugated systems could not only be used as enrichment carriers but also be in favor of electron transport in the electrochemical detection. The NPB-modified electrode was fabricated for the simultaneous detection of catechol (CA) and hydroquinone (HQ) to enhance the signal-to-noise ratio and further improve the sensitivity. A detection limit as low as 37 and 47?nM was achieved for CA and HQ, respectively. The proposed strategy with the merits of high sensitivity, selectivity, and reproducibility exhibited a great potential for the detection.