How to write a labor relationship certificate and how to prove a labor relationship

Sample text for writing a certificate of labor relations:

Certificate of labor relations

This is to certify that XXX, male, XX years old, Han nationality, ID number XXXXXX, registered place of residence XXXXXXX was engaged in XX work in our unit from XX month XX, XX year to XX month XX, XX year. Now the contract has expired. After negotiation, both parties voluntarily settled the contract.

This is to certify

XXXXX unit

Responsible person: XXX

Year, month and day