The primary objective of this trial is to demonstrate that the fixed-dose combination of T80/HCTZ25 is superior as first line therapy in reducing seated trough cuff Systolic Blood Pressure(SBP) compared to the monotherapy of T80 in patients with grade 2 or grade 3 hypertension (SBP>=160 mmHg and Diastolic Blood Pressure(DBP)>=100 mmHg).