Objective: To investigate the localization and co-expression of heat shock protein 70 (HSP70) and P53 in the human embryonic lung (HEL) cells treated by benzo(a)pyrene (BaP). Methods: HEL cells were cultured and treated at different concentrations of BaP (0, 10, 50, 100, 200 μmol · L-1) for 3 hours. The expressions of P53 and HSP70 were detected by immunohistochemistry and Confocal Laser Scanning Microscopy technology. Results: The expression of HSP70 was detected in both the nucleus and cytoplasm in BaP-treated HEL cells, and the expression mainly concentrated in the nucleus when the concentration of BaP was increasing. A similar distribution of P53 protein was observed in BaP-stimulated HEL cells, however, the levels of P53 in the nucleus were higher than that in the cytoplasm. The co-expression of HSP70 and P53 was found in the cytoplasm at the dose of less than 50 μmol · L-1, and in the nucleus at the dose of more than 50 μmol · L-1 BaP. Conclusion: The immunolocalition and distribution of HSP70 and P53 in HEL cells treated by benzo(a)pyrene(BaP) is in a dose-dependent manner, and the localization of co-expression of HSP70 and P53 is changed from the cytoplasm to the nucleus as BaP concentration increasing.