A locking device of a front fork with shock absorber and releasing pressure structure therewith, when users came across accidented terrain while riding and the buffering function of the front fork is turned off, the counterforce is transmitted to the front fork and exceeded the threshold value of the hydraulic oil, so that the damper and the plug piece move upwardly to compress the elastic member and the through holes of the damper are opened to make the hydraulic oil of the lower fork tube flow to the upper fork tube, thus the upper and lower fork tubes can be moved oppositely. When the counterforce is less than the minimum force of compressing the elastic member, the elastic member is pressed against the plug piece, and the damper can be repositioned and the through holes will be closed again.