In plants, heptahelical proteins (HHPs) have been shown to respond to a variety of abiotic stresses, including cold stress. Up to the present, the regulation mechanism of HHP5 under low temperature stress remains unclear. In this study, was isolated from Pak-choi ( ssp. cv. ). Sequence analysis and phylogenetic analysis indicated that in Pak-choi is similar to in . Structure analysis showed that the structure of the BcHHP5 protein is relatively stable and highly conservative. Subcellular localization indicated that was localized on the cell membrane and nuclear membrane. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that was induced to express by cold and other abiotic stresses. In Pak-choi, -silenced assay, inhibiting the action of endogenous , indicated that -silenced might have a negative effect on cold tolerance, which was further confirmed. All of these results indicate that might play a role in abiotic response. This work can serve as a reference for the functional analysis of other cold-related proteins from Pak-choi in the future.