Plant is frequently exposed to various pathogens environments during its growth and can withstand most attacks by inducing appropriate defense systems. Most of the NHL genes appear to be involved in pathogen-resistance mechanisms in higher plant. The steady-state transcription levels of some NHL genes could be altered when plants were attacked by bacterial pathogens. NHL-like proteins play important roles in the defense systems in higher plants. In this study, bioinformatics approach was utilized for analyzing nucleotide and amino acid sequences of AgNHL gene, which were cloned from celery (Apium graveolens) cultivars ‘Jinnan Shiqin’ and ‘Meiguo Xiqin’, respectively. Sequence analysis indicated that the AgNHL gene contained a 636 bp ORF, which encoded 211 amino acid residues. There is only one nucleotide site and no amino acid site difference between the AgNHL genes from two cultivars of celery. NHL-like protein of celery has a high homology with other higher plants, such as Vitis vinifera and Glycine max. Among the amino acids, 80-185 has a conserved domain: LEA-2. Real-time quantitative PCR analysis showed that the AgNHL gene was tissue-specific expressed mainly in the stem in celery, but expression level is low in the root. The expression profiles of the AgNHL gene were also detected by real-time quantitative PCR under 4 oC, 38 oC, NaCl and PEG treatments for 2 h in the two celery varieties. The gene expression was significantly induced under low temperature and salt stresses.