Abstract: In this paper, an electrochemical sensor was constructed by encapsulating rat adrenal pheochromocytoma (PC-12) cells with sodium alginate (SA) and polyelectrolyte membrane (PEM) to study the effects of the cell-baesd electrochemical properties of benzo (a) pyrene (BaP). A new method for the determination of BaP was established. As recognition elements, rat adrenal gland pheochromocytoma (PC-12) cells wrapped in the protection of SA and PEM were immobilized on the electrode. Eventually, analytical determination was performed by electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV) and cyclic voltammograms (CV). The results indicated that BaP caused a marked decrease in electrochemical impedance in a dose-dependent manner in range of 1~5 μmol/L with a detection limit of 0.21 μmol/L, the linear equation was:y=-418.660x+4234.706, r=0.994. The average recovery rate was higher than 97% and the RSD of the test result was less than 5%, indicating that the sensor had the good reproducibility and stability. Overall, the method for BaP sensor detection established in this study was a cheap and simple method with high stability and reproducibility, providing a new idea for the study of BaP.