Abstract: The aim was to elucidate the effects of photoperiod regulation on the directional shaping of plant architecture and yield in dwarf rice. The previously established rice Bowman-Birk trypsin inhibitor（BBTI13） gene knockout line（SR107), which exhibits reduced photoresponsiveness, was used as the experimental material. Long-day（16 h light/8 h dark）and short-day（8 h light/16 h dark）conditions were created in a climate chamber to treat the mutant line（SR107）and wild-type（Nipponbare）seedlings. Following cultivation in the climate chamber and in the field, the effects of photoperiod duration on their seed morphological characteristics, agronomic traits, yield and thousand-grain weight were analysed separately. The results indicated that the mutant line exhibited significant differences in agronomic traits under long- and short-day conditions. Compared with the wild type, long-day conditions stunted the plants, while short-day conditions caused them to revert to a normal plant type. This finding was also verified in field experiments under different day-length conditions. Furthermore, under controlled environmental chamber conditions, long- and short-day treatments primarily affected seed width. Following the field planting of mutant strain seedlings after 7～14 days of long- or short-day treatment, it was observed that the yield per plant, total number of grains per plant, number of filled grains per plant and thousand-grain weight were all lower for the mutant strain than for the wild-type after long-day treatment. Conversely, yield per plant and thousand-grain weight increased after short-day treatment. This study revealed that short-day treatment can restore the plant height of dwarf rice and increase its yield, providing a theoretical basis for the targeted improvement and molecular breeding of this crop.