In this paper, a body sensor network (BSN) system for measuring systolic blood pressure (SBP) by a cuffless approach based on h-Shirt has been developed. Two experiments were conducted on a total of 22 subjects to evaluate the cuffless calibration approach and BSN system respectively. The results showed that using the estimated time and distance travelled by a pulse and a parameter derived from the secondary derivative of PPG, the BSN system can measure SBP completely without using a cuff within 1.2??6.0 mmHg of the reference on 10 healthy subjects aged 21-35 yrs.