Small conductance calcium-activated potassium channel (SKCa) is the key factor in the regulation of endothelium-dependent vasodilatation. The aim of this study was to measure the expression levels of SK2 mRNA and protein in hypertension (HT) and normotensive (NT) patients. Mesenteric arterial tissues were collected from the removed tissues by abdominal operations in Han Chinese normotensive and primary hypertensive patients. The human tissue collection protocol was approved by the Ethics Committee of Luzhou medical College. In the present study, informed consent was obtained from the patients for the use of vascular tissue (which is usually discarded). Hypertension was defined as systolic blood pressure ≥140 mm Hg and diastolic pressure ≥90 mm Hg according to the Chinese and international diagnostic criteria of hypertension guidelines. mRNA and protein of mesentery artery were obtained from 8 NT and 8 HT patients. The expression of mRNA was detected using quantitative Real-time PCR and analyzed with 2(-ΔΔCT) method. The artery protein extractions were detected using western blot with SK2 antibody. The statistical analysis was done using independent-samples T test by SPSS 17.0. The average age of HT was 59.2500±1.2256, while the age of NT was 56.6250±8.7331. Real-time PCR and western blot experiments of each sample were repeated for 3 times and the average of the data was for analysis. The expression level of SK2 mRNA in HT was reduced by 38.3%, compared with normal arterial pressure patients. The relative expression of SK2 protein in HT was 1.0387±0.4535, while it was 1.7269±0.5825 in NT, P<0.05. There was significant difference in these two groups. Expression levels of SK2 mRNA and protein were significant down-regulation in essential hypertension patients. It may be another important factor in regulating SKCa channel activity. That may lead to the abnormal of vascular smooth muscle hyperpolarization and the occurrence of hypertension.