The invention relates to a method and a device for improving the blood vessel hardness measuring accuracy based on pulse wave frequency spectrum analysis, wherein, the method is realized by the steps that a pulse signal is acquainted, a universal pulse signal preprocessing process is performed; a pulse signal through preprocessing is read by a single-chip microcomputer; the base line leveling up treatment and the normalization treatment are performed to a pulse wave signal; the initial filtering treatment is performed to the pulse signal; the parameter of an energy domain entropy power value is calculated; the statistical analysis is performed to a frequency domain result, and the secondary filtering is performed. The device comprises an armband, a gas transmission hose connected with the armband, an air pump and a control valve respectively connected with the gas transmission hose, a sensor installed on the armband, an A/D converter respectively connected with the sensor and the single-chip microcomputer, and a valve drive unit and a pump drive unit respectively connected with the single-chip microcomputer. The invention can perform the selectable large area frequency band filtering, the filtering-off not only comprises a noise signal not removed by the initial filtering, but also comprises a useless frequency band signal, the useless data treatment is avoided, to ensure that the calculation of the blood vessel hardness is more accurate, and the calculation has pertinence.