Objective To study the subcellular localization signals of cytokinin receptors and related mechanisms.Method A series of expression vectors for subcellular localization of Arabidopsis histidine protein kinase 3 (AHK3), one of cytokinin receptor proteins in Arabidopsis, were constructed and transformed into Arabidopsis protoplast cells for transient expression. Laser confocal microscope was used to observe the subcellular localization of AHK3 protein.Result AHK3 is localized in endoplasmic reticulum(ER). Both N and C terminals contain ER localization sequences.Conclusion AHK3 carry out its functions in ER, such as perception of cytokinin, downstream signal transduction and interactions with other receptor proteins, and AHK3 contains multiple ER localization signals.