The invention provides a blood pressure measuring device, a method for effectively improving the blood pressure measuring accuracy on the basis of the measuring device and a method for judging moments of the closed state and the open state of an artery blood vessel. A blood pressure value is accurately obtained through continuous collection of Korotkoff vibration signals, detection of heartbeat periodic waveforms and extraction of fixing belt pressure signals. The problems that an existing sphygmomanometer is easily disturbed and the detection reliability is limited are effectively solved, a functional relationship of the Korotkoff vibration signals and the heartbeat period of the human body can be accurately and effectively recognized, and therefore the human body blood pressure accuracy value is accurately determined. The device can collect multiple physiological parameters at the same time, and provides data supports for related medical diagnosis and scientific research. The measuring device and method are applicable to the multiple fields of conventional blood pressure measurement, clinical diagnosis of related diseases of the heart, blood vessels, blood and the like, family health care and the like.