The utility model provides a hydraulic sealing series assembly with the adjustable thickness. The hydraulic sealing series assembly is composed of a set of thickness series annular washers, a circle of sealing groove is formed in one side of each washer, and an O-shaped sealing ring is embedded in each sealing groove. The set of thickness series washers comprise one washer with the base thickness being H and three washers with the base thickness H added with integral multiples of the 1/4 screw pitch L, wherein the integral is one or two or three, and accordingly the set of series washers with the thicknesses being H, H+L/4, H+L/2, and H+3L/4. The hydraulic sealing series assembly with the adjustable thickness can solve the problem that a communication cable is broken due to the fact that the wiring direction of a displacement sensor of an auxiliary recoiler arm holding cylinder is not in place, and the operability of the set is improved. The sealing effect is effectively improved, oil leakage is avoided, oil consumption is lowered, and the operation environment can be better improved. The accident of displacement sensor damage due to the fact that the wiring direction can not be adjusted is avoided, and the service life of the displacement sensor is prolonged. The hydraulic sealing series assembly can be widely applied to adjusting the direction of a hydraulic equipment oil pipe connecting bend.