Sweet potato is an important food crop and economic crop, yet its growth is frequently constrained by environmental factors and agricultural practices. To explore the effects of different plant growth retardants on the agronomic traits of sweet potato seedlings, three plant growth retardants, paclobutrazol, uniconazole and mepiquat chloride, were selected, and their effects on the growth of sweet potato seedlings were studied by root irrigation. The results showed that while the three retardants did not significantly affect the aboveground growth of sweet potato, they notably promoted root length and root fresh weight. Among them, the number of roots increased by 58.11%, the root length increased by 27.38%, and the root fresh weight increased by 36.17% after the treatment of 1.5 g.ai/ha. When uniconazole was treated with 15g.ai/ha, the number of roots increased by 39.05% and the fresh weight of roots in-creased by 72.11%. The number of roots increased by 17.65%, the root length increased by 22.72%, and the root fresh weight increased by 47.84% when treated with mepiquat chloride at 1.5 g.ai/ha. The findings provide a theoretical basis and technical support for further optimization of sweet potato cultivation and management, contributing to improved yield and quality, and promoting the sustainable development of the sweet potato industry.