This study analyzed the exponential decay characteristic of the harmonic peaks in the spectrum of blood pressure wave (BPW) from radial artery at wrist. Low-order harmonic deviation (LHD), high-order harmonic deviation (HHD), total harmonic deviation (THD) and exponent (alpha) were developed to assess the exponential decay feature of normal subjects (N group) and the patients with palpitation (P group). The statistical results indicate that only the HHD (p value=0.01<0.05) of N group is significantly less than that of P group while LHD (p value=0.08>0.05), THD (p value=0.22>0.05) and alpha (p value=0.23>0.05) make no significant differences. The results imply that the spectral harmonic peaks for patient subjects exhibit more severe deviations in high-order harmonics along the exponential decay curve than those for normal subjects. In conclusion, this paper proposes a novel viewpoint to observe how the heart distributes blood into arterial system under normal and abnormal situations in spectral domain.