Abstract: A self-developed air purification device using negative ions and photocatalytic oxidation technology was adopted to perform the experiment in indoor to evaluate the tobacco smoke cleaning efficiency. The color analysis (RGB contrast) method was used for evaluation the purification rates of fine particulate matter (PM_2.5). The experiment results indicate that photocatalytic oxidation technology shows significant effects of purifying NO_x and negative ions play an important role on cleaning PM_2.5. The purification device can effectively purify the cigarette smoke.