Objective: To investigate the pulmonary protective effects of short-term leukocyte depletion with a modified filter located at the CPB venous line in canine. Methods: Sixteen healthy hybrid canines were randomly allocated to the LD-1 group, with an LD-1 filter installed in the CPB venous-line for a 5-minute leukocyte depletion at the beginning of the CPB, and to the control group. Blood samples were taken for routine test respectively at 9 time-points, namely pre-CPB, at 5, 10, 40, 70 min of the CPB, 5 min after aortic cross-clamp being off, at the discontinuation of the CPB, 5 min after protamine being administered, and 2 h after the CPB. Oxygen index (01), pulmonary pathology and levels of interleukin-6 (IL-6) and interleukin-8 (IL-8) in plasma were measured at pre-CPB, 5 min after protamine being administered and 2 h after the CPB respectively. The levels of IL-6 and IL-8 in the bronchial alveolar lavage fluid (BALF) were measured at 2 h after the CPB. Results: In LD-1 group, white blood cell (WBC) counts were significantly less than those in control group at 5 min of the CPB (P < 0.05), the filtration rate of WBC was (65.72 ± 9.36)%. The WBC counts showed no significant difference in either group from 40 min of the CPB to 2 h after the CPB. OI was higher in LD-1 group than that in control group (P < 0.05) at 5 min after protamine being administered and 2 h after the CPB. There was significantly less WBC infiltration and alveolar edema of the lung in LD-1 group than that in control group at 5 min after protamine being administered and 2 h after the CPB. There were no significant differences of IL-6 and IL-8 in plasma between the two groups at 5 min after protamine being administered (P > 0.05), but the levels of IL-6 and IL-8 were much lower in the LD-1 group than those in the control group at 2 h after CPB. At 2 h after the CPB, IL-6 level in the BALF showed no significant difference in each group (P > 0.05); however, the level of IL-8 was lower in LD-1 group than that in control group (P < 0.05). Conclusion: The LD-1 filter in the CPB venous-line in canine model used for short-term leukocyte depletion filtration could reduce WBC counts significantly, decrease the levels of IL-6 and IL-8 in plasma, attenuate inflammatory response in the lung after CPB, so it has protective effect on canine lung.