In this article, we studied how meditation affects the characteristics of the cardiovascular system, mainly based on blood pressure waveforms (BPW). Four parameters derived from BPW include the rising slope (h1/t1), normalized height of T wave (h3/h1), normalized height of V3 valley (h4/h1) and normalized height of D wave (h5/h1), where t1 and hi, i = 1, … ,5 are quantitative features of the BPW waveform pattern. A larger value of h1/t1 reflects better heart ejection ability and aorta compliance. A larger value of h3/h1 may infer an arterial system with good elasticity. The decrease (increase) of h4/h1 parameter indicates the decrease (increase) of peripheral resistance of vessels. A larger value of h5/h1 indicates better artery elasticity and aortic valve function. In comparison with the control group, Zen-meditation practitioners have more after-meditation h1/t1, h3/h1 and h5/h1 increase, with more h4/h1 decrease, with statistical significance (P < 0.05). The observation allows us to infer that Zen meditation may effectively improve relevant characteristics of the cardiovascular system.