Abstract: A new instrument is developed to detect hemodynamic parameters, which needs not measure blood pressure beforehand and therefore more convenient. Integrated with a blood pressure measuring module, this system can measure blood pressure value automatically. The signal of pulse wave can be detected by a pulse pressure sensor, amplified and filtered, and finally transferred into digital signal used in PC by means of an A/D converter. Making use of double elastic cavities module, the software of this system can work out hemodynamic parameters such as heart rate, coefficient of pulse wave, and so on based on basic information of patient including blood pressure value. Demonstrated by comparison experiment and repeatability experiment, this system possesses high accuracy and good repeatability and thus can be applied to clinic and family health care.