Based on the genome-wide expression profile of cotton seedlings under low phosphorus stress in the early stage of our research group and the genome database, we cloned a AP2/ERF gene (GhERF5) from upland cotton ‘Xinluzao 19’. Genomic DNA and cDNA sequence of the gene were cloned and analyzed by bioinformatics method. We used semi-quantitative RT-PCR and real-time PCR (qRT-PCR) to detect the gene expression changes in roots, stems, leaves, flowers and other tissues, as well as the relative expression of the gene at different time points under low phosphorus stress.The results showed that: (1) the AP2/ERF gene, named GhERF5, was successfully cloned. The length of open reading frame was 963 bp, encoding 320 amino acids. Analysis revealed that this gene sequence belonged to the AP2 family, with a conserved structure named AP2. (2) Sequence alignment analysis showed that the similarity of Gossypium arboreum L. (GaERF5) and Gossypium raimondii L. (GoraiERF5L) was 95%. Evolution analysis showed that the similarity between the GhERF5 protein sequence of G.hirsutum L. and the GhERF5L of G.hirsutum L. was the highest. It was speculated that the GhERF5 gene was located in the D sub-genome. (3) RT-PCR and qRT-PCR analysis showed that GhERF5 was expressed in all tested tissues including root, stem, leaf and flower, and the expression level was the highest in leaf, followed by root and stem, and the expression was the lowest in flower, and the change trend of low phosphorus treatment from 0-72 h was first decreasing, then rising and then decreasing, and at 72 h, low phosphorus treatment was about 33% that of suitable phosphorus treatment. This study demonstrated that GhERF5 gene belongs to low phosphorus stress response gene and may be involved in G. hirsutum L. response to low phosphorus stress.