To evaluate the effect of punctal occlusion on tear preservation after third eyelid resection, 10 eyes were operated in dogs and observed changes in tear preservation using Schirmer tear test (STT). Punctal occlusion was performed on five healthy dogs with no clinical sings of ocular irritation and no history of dry eye syndrome. The STT was performed for 10 days before surgery, and on the day 0, 1, 3, 5, 7, 9, 11, 13, 17, 21, 25, and 30 after third eyelid resection. The mean STT was $17.4{pm}0.15$ mm/min($mean{pm}SEM$) for 10 days before surgery. And, it was $11.5{pm}0.55$mm/min for 30 days after surgery in puntal occlusion(PO) group. The mean STT was $17.3{pm}0.32$ mm/min for 10 days before surgery. And, it was more decreased to $6.5{pm}0.60$ mm/min for 30 days after surgery in control group. The paired t-test was performed. Mean STT after the third eyelid resection was higher in PO group than that of control throughout experimental period (p<0.05). In summary, the effect of thermal punctal occlusion significantly increased on the tear preservation by $28.86{pm}7.96%$. These results suggest that application of thermal punctal occulsion in dry eye syndrome will promote tear preservation.