The invention discloses a nonlinear compensator for a capacitive weighing sensor, and the compensator comprises an upper housing and a lower housing. The upper housing is located exactly above the lower housing, and the outer side surface of the upper housing is provided with a sealing pad through pasting. The external surface of the sealing pad is fixedly connected with the inner surface of a fixed frame, and the outer side surface of the lower housing is provided with two closed grooves. The interior of each closed groove is provided with a sealing strip in a clamped connection manner, and an outer side surface of each sealing strip is fixedly connected with the inner surface of the sealing pad. The front surface of the lower housing is provided with a wire incoming hole and a wire outgoing hole. Parts, corresponding to the wire incoming hole and the wire outgoing hole, of the fixed frame are provided with first gaps. According to the invention, through the fixed arrangement of a first sealing ring, a second sealing ring and a third sealing ring on a line sleeve in a sleeved manner, the compensator can enhance the sealing of the joint of the line sleeve and the lower housing, can effectively avoid water immersion and wetting through binding the sealing pad between the upper housing and the fixed frame, and solves a problem that a conventional nonlinear compensator is poor in sealing effect.