Abstract: 【Objective】 This study aimed to investigate the distribution patterns and biological functions of the HSP70 gene family members in Hylocereus undatus， thereby providing theoretical basis for elucidating the molecular mechanisms underlying the high-temperature stress response of HSP70 family members in Hylocereus undatus. 【Method】 Using bioinformatic methods， the HSP70 gene family members were identified from the whole-genome of Hylocereus undatus to analyze their conserved motifs， encoded protein characteristics， gene structures， chromosomal localizations， and promoter cis-acting elements. The phylogenetic analysis and colinearity analysis were performed. Gene expression analysis and real-time fluorescence quantitative PCR were used to investigate their tissue-specific expression characteristics and the effects of high-temperature stress on relative expressions of HSP70 gene. 【Result】 A tolal of 15 HSP70 gene family members were identified from Hylocereus undatus， and they distributed across 9 chromosomes. A total of 19 motifs were identified， among which Motif 1 was a conserved motif shared by all members， and 7 family members contained more than 4 introns. Analysis of promoter cis-acting elements revealed that the HSP70 gene family contained various elements associated with stress， including those involved in hormone response， stress response， as well as growth and development regulation. Phylogenetic and gene colinearity analysis results indicated that： the HSP70 gene family in Hylocereus undatus was divided into 3 major groups； there was no colinearity with the HSP70 gene family in Arabidopsis thaliana， but significant colinearity existed with the HSP70 gene family in Beta vulgaris. Gene expression analysis results showed that the expression of Hylocereus undatus HSP70 gene family members was tissue-specific，two of which showed specific expressions in pulp，and one of which showed specific expressions in areole. Real-time fluorescence quantitative PCR results showed that， compared to the control， the relative expressions of the five genes were significantly up-regulated after high-temperature stress treatment. Among them， the HU07G00259.1 gene exhibited the greatest up-regulation， with its relative expression increasing approximately by 40 folds compared to the control. 【Conclusion】 A total of 15 members of the HSP70 gene family in Hylocereus undatus were identified： HU01G00744.1， HU01G00501.1， HU05G01041.1， HU07G00259.1， and HU04G01697.1 are significantly up-regulated under high-temperature stress treatment， demonstra-ting distinct high-temperature response characteristics. Among these， the HU07G00259.1 gene is likely a key regulatory factor in the high-temperature response of Selenicereus spp. vines.