Platanus acerifolia is one of the most widely used ornamental trees in gardens and streets. Growth-regulating factors (GRFs) are a type of transcription factors that regulate growth and development and interact with GRF-interacting factors (GIFs). However, the GRF and GIF transcription factors of P. acerifolia remain unreported. Here, we systematically identified ten GRF (PaGRFs) and three GIF (PaGIFs) genes in P. acerifolia. Subsequently, the characteristics of the PaGRFs and PaGIFs were determined using bioinformatic analysis. Promoter cis-element prediction analysis showed that most of the PaGRF and PaGIF promoters contained plant hormone-related cis-elements and plant hormone response analysis showed that both PaGRFs and PaGIFs responded to indole-3-acetic acid, 6-benzylamino purine, brassinolide, abscisic acid, gibberellin A3, and a strigolactone analog. Additionally, the expression levels of several PaGRFs and PaGIFs in the axillary buds of P. acerifolia seedlings decreased after topping. All ten PaGRF genes contained a target site for Pa-miR396 and their expression patterns in leaves of different stages showed that PaGRFs and PaGIFs had higher expression levels in young leaves; however, Pa-miR396b had the contrary pattern. A yeast two-hybrid assay indicated that various PaGRF proteins interacted with the three PaGIF proteins. Overexpression of Pa-miR396 in Arabidopsis resulted in smaller and narrower leaves and the expression levels of AtGRFs, cell cycle-related genes (AtCYCB1;1, AtCYCD3;1, and AtKNOLLE), and cell expansion-related genes (AtSAUR and AtEXP10) showed significantly decreased levels in Pa-miR396-transgenic plants. Overall, the results of this study provide a theoretical basis for leaf development in the controlled breeding of P. acerifolia.