I haven't bought social security before, but now I'm in a new company. Do I need to pay an unemployment certificate to buy social security?

Signing a labor contract is the most important thing for any unit. You can buy all kinds of social security only after signing a labor contract. You didn't sign a contract in the first company, which means that you are not unemployed within the scope of the labor law, so you will definitely not get the unemployment certificate. Of course, the scope of handling unemployment certificates has been extended to those who have not found a job for a long time after graduating from college or technical secondary school. So the first thing you do when you arrive at the new company is to sign a labor contract to determine the labor relationship, and then the company will handle the relevant social security for you. Of course, the company you are looking for will provide you with social security, otherwise it will be empty talk.