Cardiovascular disease is an abnormal function of the heart or blood vessels which have become major causes of deaths in recent years. Moreover, the number of patients of cardiovascular diseases and diabetes increases year by year. Since the blood pressure waveform is suggested to be related to arterial-pulse wave transmission, it may have important meaning in the study of cardiovascular disease. Many methods can be used to noninvasively assess the arterial blood pressure waveform; however they often suffer from not being user-friendly in practical application or too expensive cost, such as CT or MRI scan. PPG (PhotoPlethysmoGraphy) is an optic signal related to the arterial volumetric pulsations of blood and has great potential value in clinical applications owing to its simplicity and noninvasiveness.Therefore, in this study, I have developed and implemented a real-time non-invasive PPG system to measure the blood flow characteristics. Combined with ECG (ElectroCardioGram) signal, PTT (Pulse Transit Time) is measured for conventional PPG-ECG related research. Moreover, an experiment protocol has been designed to compare PTTV (Pulse Transit Time Variability), and PRV (Pulse Rate Variability), HRV (Heart Rate Variability) under the negative stimulus. In previous study, we have confirmed that HRV decreased under the negative conditions. The result of this experiment demonstrated that the PTTV also declined exposed to negative stimulus. The relationship between HRV and PRV provided us an effective method for cardiovascular characteristic assessment and physiological and psychological research.