To check the validity period and related information of the chef's certificate, you can consult and inquire with the relevant local departments. Generally speaking, the issuance and management of chef's certificate is the responsibility of the health department or the food and drug supervision department. You can contact the local health bureau, food and drug administration or relevant professional associations and provide them with relevant certificate information, such as name and certificate number, so that they can check and verify. They will tell you the validity period, issuing date, certificate type and other information of the chef's certificate. The purpose of inquiring about the chef's certificate is to ensure that the chef has relevant professional knowledge and skills, and to ensure food safety and public health.