The invention discloses a mechanism for amplifying the negative stiffness coefficient and an ultra-low-frequency shock absorber composed of the mechanism, and belongs to the field of shock absorption.The mechanism is composed of one or more negative stiffness units and one or more positive stiffness units with the larger stiffness coefficient absolute value, wherein the one or more negative stiffness units and the one or more positive stiffness units are connected in series; the other two ends of the negative stiffness units and the positive stiffness units are used for being connected with ashock absorbed body and a base correspondingly; one or more negative stiffness amplifying mechanisms are connected with the one or more positive stiffness units having the appropriate stiffness coefficient and a main supporting effect in parallel and placed between the shock absorbed body and the base to form the ultra-low-frequency shock absorber; and the negative stiffness amplifying mechanismsenable the vibration displacement of the negative stiffness units to be amplified by the corresponding multiple, thus acting force which is generated by the negative stiffness units and transmitted by the negative stiffness amplifying mechanisms is amplified by the same multiple, and compared with the negative stiffness units in the negative stiffness amplifying mechanisms, the negative stiffnesscoefficients of the negative stiffness amplifying mechanisms are also amplified by the same multiple. The high negative stiffness coefficient and ultra-low-frequency shock absorption can be achievedthrough the small size, weight and cost.