Abstract: Conjugated linoleic acid (CLA) is a nutrient substance that exists in humans and animals. It has anti-tumor, anti-atherosclerosis, and immune-regulating functions, but its oral bioavailability is low. Conjugated linoleic acid dry powder inhalers (CDPIs) were prepared and intratracheally administered to the rats that suffered from primary lung cancer. Conjugated linoleic acid nanoemulsions were prepared first and CDPIs were with 10% mannitol after lyophilization. CDPIs are loose white powders with the aerodynamic median diameter (D_a) of 3.10 μm, which were suitable for pulmonary delivery. Rats lung cancer models were established after 45 days by instilling 3-methylcholanthrene (MCA) and N,N-dimethylnitrosamine (DEN) into the rats lung once. The animal experiments were approved by the Ethics Committee of Academy of Military Medical Sciences and conducted in accordance with the relevant guidelines and regulations. The CDPIs, gefitinib suspension and blank DPIs were sprayed into the lungs of rats with lung cancer through the trachea. Compared with the model group, both the gefitinib suspension group and the CDPIs group showed significantly fewer tumor nodules and inflammatory cells, and the CDPIs group was better than the gefitinib suspension group. The inhibition efficiency of CDPIs on CD31 and NF-κB p65 was better than that of the gefitinib suspension group. The vascular endothelial growth factor (VEGF) level in the CDPIs group was significantly reduced, which was equivalent to that of the gefitinib suspension group. The apoptosis in the CDPIs group by Tunel tests showed a significant increase, which was significantly better than the gefitinib suspension group. Therefore, CDPIs had excellent pharmacological activity on lung cancer, which provided a model for the efficient delivery of oil therapeutic agents.