Blood pressure (BP) is one of the most important physiological parameters reflecting cardiovascular status of people. Continuous and non-invasive BP measurement, which can provide beat-to-beat BP information and call attention to the doctor if the patent is in danger during surgery, plays a very important role in safety control in operation and intensive care. In this paper, a novel and complete methodology of continuous and non-invasive BP measurement by PWV without calibration by other methods such as cuff sphygmomanometer is proposed. Critical parts of this study include modeling BP-PWV relationship and identifying two PWVs relative to systolic blood pressure (SBP) and diastolic blood pressure (DBP) respectively. Some benchmark models for 20-year-old and 60-year-old age groups are developed and applied to BP measurement in clinical trials. The clinically obtained results meet the test standard in ANSI/AAMI SP10, which attests the feasibility of the measuring method. Lastly, the continuous SBP and DBP measurement results by PWV method are shown.