The present invention relates to the use of the overexpression of a Populus tomentosa strigolactone receptor PtoD14 gene in increasing a wood yield. By means of cloning a Populus tomentosa strigolactone receptor PtoD14 gene from wild-type Populus tomentosa and introducing the PtoD14 gene into Populus tomentosa plants by means of a genetic engineering method, a Populus tomentosa line with enhanced secondary development is obtained. The number of secondary xylem cell layers in 3-month-old PtoD14 transgenic Populus tomentosa is 8 to 21 layers more than that in 3-month-old non-transgenic common Populus tomentosa, which is of important significance for providing a high wood yield for the large-scale production of Populus tomentosa.