Abstract: Root excision mulched with film is an effective method which can minimize decrease in crop production in negative-effect area. However, the measure may have adverse effects on the cropland shelterbelt. Taking no treatment as CK, the effects of root excisions mulched with film at distance 0.5, 1, 2 and 3 m from the trunk on photosynthesis characteristics of poplar shelterbelts in black soil region were discussed. The results indicated that root excision mulched with film had no significant effect on poplar leaf water content. Early in July, the time of peak and trough in the treatments were earlier than CK. Different treatments of root excision mulched with film made daily average value of net photosynthetic rate of poplar leaves significantly lower than CK, and there were significant difference among different treatments. During August to September, root excision mulched with film induced daily average value of net photosynthetic rate of poplar leaves still lower than CK, but the lowered range was somewhat reduced, root excision mulched with film at the distance 3 m from the trunk had no significant difference from CK. After root excision mulched with film, transpiration curve appeared in many forms. At the distances 2 and 3 m from the trunk, daily average value of transpiration rate of poplar leaves had no significant difference from CK. At the distances 0.5 and 1 m from the trunk, the decrease in transpiration rate in July was greater than that of photosynthetic rate, resulting in the significantly high water use efficiency than CK. Compared with CK, daily dynamics of water use efficiency in the other treatments had no change, however, daily average value of water use efficiency in the other treatments had significant change, and some of the changes were adverse. Comprehensive comparison indicated that root excision mulched with film at the distance 3 m from the trunk had no significant effect on the photosynthetic characteristics of poplar leaves, and this treatment was significantly superior to others.