The growth-regulating factor (GRF) transcription factor is a plant-specific gene family that regulates plant growth. In Arabidopsis and rice, the GRF gene family-encoding proteins have a positive function in regulating stem and leaf growth and development. In the present study, we speculated that the GRF genes might be more important and responsible for the formation of narrow leaves. To ask if the GRF genes are the causal mechanism in the development of a narrow-leaf peach variety (Prunus persica ‘Jin Mi Xia Ye’), GRF genes in the peach genome were identified by BLAST search according to the sequence homology. The expression pattern of these GRF genes was determined in the shoot apical meristem, young leaves, mature leaves, seeds, flesh of fruit, and phloem in ‘Jin Mi Xia Ye’ and the normal-leaf variety ‘Chinese Cling’. Meanwhile, the genetic mapping of narrow-leave was conducted in an F2 population by using 126 simple sequence repeats (SSR) markers. Ten members of the GRF genes were found in the peach genome. The deduced proteins of GRFs arranged from 191 and 612 amino acids. Sequence analysis showed that the N terminal of these proteins maintained two conserved motifs QLQ (Gln-Leu-Gln) and WRC (Trp、Arg、Cys), except that the Leu residue of QLQ in ppa011917m was replaced by Phe. While the C terminal of those sequences varied, for instance, a TQL and a GGPL motifs. A phylogenetic tree using a neighbor-joining method placed the GRF genes into three groups. According the expression result of 10 GRF genes in peach, six of them exhibited higher expression levels in the shoot apical meristem than in young leaves and other mature tissues and organs. Only a few genes showed slight expression levels in the flesh of fruit, mature leaves, and phloem, such as ppa022199m in flesh and ppa019752m in phloem. Only two genes, ppa019623m and ppa003017m, expressed higher levels in peach varieties with narrow leaves than in those with normal leaves. Meanwhile, we located the narrow-leaf trait in the region between two markers (UDP98-407 and BPPCT025 of linkage group 6) using linkage analysis based on SSR markers. Based on the linkage analysis, we then chose the ppa003017m as one of the key candidates in regulating leaf development in the ‘Jin Mi Xia Ye’ variety. However, the sequence amplification found that, among 30 seedings with different leaf phenotypes, no variation existed in the promoter of the key candidate gene, ppa003017m. The results indicate that there is no relationship between the expression of ppa003017m and sequence variation in its promoter regions. This study highlights the importance of identifying genes that regulate the narrow-leaf trait in peach, as well as the importance of selecting the excellent peach germplasm resources with high photosynthesis efficiency using molecular marker assisted selection in the future.