The invention discloses a shock absorber capable of changing damping and adjusting mass and rigidity and a rigidity quantitative regulation method. The shock absorber comprises a base, two rubber washers, a mass block, a top end cover, a nut, a screw rod, an internal end cover, a lining, a regulating stopper, a rubber sleeve and a guide rail seat. When a system vibrates, the mass block vibrates under support of the rubber washers to absorb part of energy, and the interior of each of the rubber washers vibrates to consume part of energy, so that the purpose of realizing vibration attenuation ofa main system is realized. Mass regulation of the shock absorber is realized through the number of the mass block; vibration of the external diameter of the lining is controlled through the depth screwed into the regulating stopper to adjust damping of the shock absorber; the top end nut is screwed to adjust the compressing degree of the upper and lower rubber washers; quantitative regulation ofthe shock absorber rigidity is realized according to the relationship of the compression amount and the compressing rigidity of the rubber washers, and a better damping effect is realized without an experiment. The shock absorber is simple and compact in structure, can realize quantitative regulation of rigidity and mass and is wide in applicable range.