Purpose To investigate the effects of Tai Chi breathing training on blood pressure, heart rate, EEG and mood in seniors with essential hypertension. A total of thirty-six essential hypertension women (aged from fifty to sixty-two years) were recruited. They were randomly divided into Tai Chi breathing training group (Tai Chi; n = 20) and control group (C; n = 16). All subjects in Tai Chi group completed 3 times 40-min Tai Chi breathing training protocol per week for 20 weeks. Blood pressure (BP; SBP/DBP), heart rate (HR), EEG (F3, F4, T3, T4, O1, O2), Beck Depression Inventory score (BDI score), self-efficacy, and life-satisfaction were measured. Repeated measures ANOVA and t-test were used to analyze the differences of pre-/post 8wks/post 20wks and between the groups. Results In Tai Chi group, SBP decreased 18.55 ± 6.32mmHg and 14.45 ± 5.64mmHg, respectively after 8 wks and 20 wks of the Tai Chi breathing training when compared to pre-test (P<.05). DBP also decreased 9.6 ± 7.44mmHg and 8.85 ± 8.21mmHg, respectively after 8 wks, and 20 wks of the Tai Chi breathing training (P<.05). The largest decrease in SBP (−12.2%) and DBP (−10.5%) were both found at week 8. Although no further decrease in SBP and DBP were found after that, the decreased levels were maintained during the remaining Tai Chi breathing training period. Although no significant change of HR was found during all the Tai Chi breathing training period, there were significant decrease in BDI score (8.0–14.5%, P<.05) combined with significant increase of self-efficacy (25.8–41.5%, P<.05) and life-satisfaction (11.3–15.0%, P<.05) after 8 wks and 20 wks of the Tai Chi breathing training. In C group, there were no significant changes in SBP, DBP, HR, BDI score, self-efficacy, and life-satisfaction after 8 wks and 20 wks. Compared two groups, there were significant differences in SBP (p<.05), DBP (p<.05), BDI score (p<.05), self-efficacy (p<.05), and life-satisfaction (p<05) both in week 8 and week 20. There were no significant differences in HP and EEG between the groups and between pre-/post 8wks/post 20wks both in Tai Chi and C group. Conclusion It is the first study about the Tai Chi breathing training on BP, HP, EEG and mood in essential hypertension seniors. The results indicate that the Tai Chi breathing training is very simple and effective way to reduce blood pressure and has shown positive influence on the mood factors and quality of life in seniors with essential hypertension. The most beneficial effects of the Tai Chi breathing training on BP and mood are observed within 8–20 weeks in this study. Further investigation is needed for a better understanding the effects on HR and EEG after a long-term Tai Chi breathing training.