Waste rubber regenerating process and waste rubber regenerant

The present invention relates to a regeneration process of vulcanized waste and old rubber and its waste rubber regenerating agent. It is characterized by that in the mixing machine, under the condition of that its roll temp. is below 75 deg.c, the waste rubber regenerating agent can be mixed with waste rubber, thin-passed through to make the sulfur cross bond in the net-like elastic structure ofwaste vulcanized rubber to reopen link chain to make it into long-chain plastic compound and reduce breakage and degradation of main chain so as to change the waste rubber into the moldable vulcanized rubber material. Said invented regenerating agent possesses higher chain-opening effect, can raise working efficiency and reduce cost. After having been regenerated the waste rubber can retain above65-75% of performance of original rubber.