Provided is a non-invasive electronic method and apparatus for measuring blood pressure, in which the data is processed with an algorithm of non-linear fitting for recovering trend envelope of an oscillating PW by a firmware, so that the trend envelope of PW amplitude can be recovered accurately, and the obtained average pressure shows higher degree of agreement with the real situation in clinic. In this apparatus, a 3-way solenoid valve (20) is arranged between a cuff (10) and a first pressure sensor (30), wherein the common port of the 3-way solenoid valve (20) is connected with the first pressure sensor (30), the normally open port thereof connected with the cuff (10), and the normally closed port thereof connected with the air atmosphere during zeroing process. Moreover, an independent timing circuit (45) is provided additionally. In the measurement method of the present invention, the zeroing is performed with the help of the 3-way solenoid valve (20). Once a state of overtime or overpressure occurs, an gas pump (50) is immediately closed, and a quick-deflation solenoid valve (60) is opened so that the pressure in the cuff (10) is released to ensure safe application.