After the randomization, the patients will be given study drugs, and take take once-daily dose of the study drugs at 07:00-09:00 (except the day of visit). During the treatment, there will be a visit every 2 weeks, and in each visit the patients need to get the study drug for next two weeks, totally 3 times. In V3 and V4, if the patients' mean DBP ≥ 90 mm Hg, the doses will be doubled, twice a day (07:00- 09:00 in the morning and 16:00-18:00 in the afternoon), otherwise, the dosage do not change.