【Objective】Poplar is one of the tree species with the highest yield, the largest planting areas and the most suitability in the middle and lower reaches of the Yangtze River of China. However, how to improve the plantation yield and wood quality is the key issue to be solved in the practices.【Method】In this paper, the plantations of poplar clone I-69(Populus deltoides cv. I-69/55)with planting spacings of 3 m × 6 m and 6 m × 6 m were taken as the research object, and four pruning treatments were designed. Based on the measurements of diameter at breast height (DBH), tree height, height under branch, trunk diameter at different height and photosynthetic leaves area, the effects of different treatments on the average annual growth of DBH, the average annual growth of tree height, the height under branch, the average annual growth of tree volume, the leaf area index and the plumpness of trunk segments at different height were analyzed, while the pruning effectiveness of different treatments was comprehensively evaluated using the improved analytic hierarchy process.【Result】Based on the 3-year investigation, the results showed that the response of the two plantations with various planting spacings to the pruning treatments was different. Pruning treatments one and two could improve the plantation growth of DBH, tree height and tree volume in the 3 m × 6 m spacing, whereas no significant effect on growth was observed among the 4 pruning treatments in the 6 m × 6 m spacing. Compared with CK, pruning treatments significantly increased the height under branches, and decreased the leaf area and leaf area index. Although pruning treatments did not significantly affect the trunk plumpness, the pruning treatment two was favorable to the trunk plumpness for the plantations of two planting spacings.【Conclusion】In term of the comprehensive assesment, the pruning way of the treatment two would achieve the best effects for P. deltoides plantations, which is more beneficial to cultivating high quality plywood timber with straightness, large plumpness and no knots.