The invention discloses a blood pressure measuring method. According to the method, the principle that correlation between amplitude of blood oxygen volume pulse wave signals and continuous blood pressure is high is utilized, an expression between pulse wave transmission time and the blood pressure in the prior art and an expression between the amplitude of the blood oxygen volume pulse wave signals and the blood pressure are fit, the incidence relation among a continuous blood pressure waveform, pulse wave transmission time x and the amplitude y of characteristic value points is determined, and then an accurate blood pressure value is obtained.