A method of monitoring blood pressure is provided. The method comprises: calculating an estimate of deviations between every two pulse transit time (PTT) values measured at an interval of a first period, using PTT values measured for a predefined amount of time, and estimating a PTT value to be measured the first period after a current time, based on the PTT value deviation estimate and a PTT value measured at the current time； calculating an estimate of deviations between every two oxygen saturation values measured at an interval of a second period, using oxygen saturation values measured for the predefined amount of time, and estimating an oxygen saturation value to be measured the second period after the current time, based on the oxygen saturation value deviation estimate and an oxygen saturation value measured at the current time； and calculating current systolic blood pressure and diastolic blood pressure based on an electrocardiogram (ECG) value measured at the current time, the estimated PTT value and the estimated oxygen saturation value.
