B[a]P and NNK were used as the target compounds. CSC and NNK in the dose of 0(CK), 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16 mg/mL respectively and B[a]P in the dose of 0(CK), 0.000 8, 0.001 6, 0.002 4, 0.003 2, 0.004, 0.004 8, 0.005 6, 0.006 4 mg/mL were tested by MTT to investigate their cytotoxicity on BEAS2B cells. The result showed the IC50 of cigarette smoke condensates (CSC), NNK and B[a]P were 0.133, 0.110, 0.004 6 mg/mL respectively. CSC combined with low dose of B[a]P and NNK respectively or together showed larger cytotoxicity than CSC alone, and CSC with B[a]P and NNK respectively displayed synergism. Low dose of CSC and NNK respectively or together combined with B[a]P showed cytotoxicity greater than B[a]P alone, and CSC and NNK with B[a]P respectively displayed synergism. Low dose of CSC and B[a]P respectively or together combined with NNK showed antagonism. The unification of B[a]P, CSC and NNK showed antagonism.