The invention discloses a water supply network leakage alarm threshold selection method based on time sequence monitoring data analysis. According to the invention, alarm threshold value is updated inreal time by using the correlation among time sequence data from a plurality of pressure sensors, and leakage alarm is carried out after the real-time monitoring index exceeds the alarm threshold value. The method comprises the following steps: (1) establishing a leakage pressure residual matrix and a non-leakage pressure residual matrix; (2) constructing a space-time maximum correlation matrix;and (3) acquiring the cumulative probability distribution of the maximum correlation coefficient, and selecting a threshold value. According to the method, under the condition that the false alarm rate (false alarm rate) is given, the alarm threshold value can be minimized, the real-time leakage identification rate is further improved, and the method has important significance for improving the comprehensive performance of a leakage alarm system.