Does it take 20 years to buy social security after 80s?

No need. According to "People's Republic of China (PRC) Social Insurance Law", the old-age insurance must be paid for at least 15 years (including deemed payment), and the pension benefits can only be enjoyed after reaching retirement age (60 years for male employees, 50 years for female employees and 55 years for female cadres), so it is not necessary to pay for 20 years to buy social security after 80s. Social insurance is a social and economic system that provides income or compensation for those who lose their ability to work, are temporarily unemployed or suffer losses due to health reasons.