The invention discloses a periodic Web access behavior detection method and a system, and a storage medium. The method comprises the following steps: obtaining a first time sequence; calculating an autocorrelation function of the first time sequence to obtain a first candidate period value; performing fast Fourier calculation on the first time sequence to obtain a second candidate period value; and performing approximate intersection calculation on the first candidate period value and the second candidate period value to obtain a period value. The method is suitable for rapid and accurate period detection functions with different period lengths.