The invention discloses a lowness extracting method of LWF storage type acoustic wave logging. The method comprises the steps that first, waveform data of logging acoustic waves are obtained; second, a head wave negative peak sequence ti of waves receiving by an acoustic wave receiver R1 in a acoustic wave logging depth domain is determined; third, acoustic wave data received by the adjusted acoustic wave receiver R1, an acoustic wave receiver R2 and an acoustic wave receiver R3 are subjected to basic line zeroing and spline fitting in the depth domain; fourth, the longitudinal wave window length and slowness s search range of the adjusted acoustic wave receiver R1 are determined; and fifth, a slowness sequence si is extracted, specifically, 501, the slowness division step length delta s is determined; 502, a slowness sequence sFi in correlation matching of a common source method is obtained; 503, slowness sRi in correlation matching of a common collecting method is obtained; and 504, the slowness sequence si of acoustic wave logging in the depth domain is calculated. The design is novel, a head wave of the acoustic waves is automatically obtained and the slowness of longitudinal waves is automatically calculated, efficiency is high, and accuracy is high.