Although plastic-covered ridge and furrow planting (RF) has been reported to produce substantial increases in the grain weight of winter wheat, the underlying mechanism is not yet understood. The present study used two cultivars, Xinong 538 and Zhoumai 18, and RF and traditional lfatten planting (TF, control) with the objective of investigating the effect of RF on wheat grain iflling and the possible relationship of hormonal changes in the wheat grains under RF to grain iflling. The results indicated that RF signiifcantly increased the grain weight, although the effects on grain iflling were different: RF signiifcantly increased the grain-iflling rate and grain weight of inferior grains, whereas RF had no signiifcant effect on grain-iflling rate and grain weight of superior grains. The ifnal grain weight of inferior grains under RF was 39.1 and 50.7 mg for Xinong 538 and Zhoumai 18, respectively, 3.6 and 3.4 mg higher than the values under TF. However, the ifnal grain weight of superior grains under RF was only 0.6 and 0.8 mg higher than under TF for Xinong 538 and Zhoumai 18, respectively. RF signiifcantly decreased the ethylene and gibberellic acid content in the inferior grains and increased the indole-3-acetic acid, abscisic acid and zeatin+zeatin riboside content in the inferior grains; however, no signiifcant difference between RF and TF was observed for the hormonal content in the superior grains. Based on these results, we concluded that RF signiifcantly modulated hormonal changes in the inferior grains and, thus, affected the grain iflling and grain weight of the inferior grains;in contrast, RF had no signiifcant effect on grain iflling, grain weight and hormonal changes in the superior wheat grains.