Can a seaman's health certificate be processed three months in advance?

Of course. The crew health certificate is valid for two years. If the crew health certificate is about to expire, you can apply for a new crew health certificate three months in advance. According to "Regulations on the Management of Seafarers' Health Examination in People's Republic of China (PRC)", a new seafarers' health examination can be conducted within three months before the expiration of the validity period, and a new seafarers' health certificate can be obtained.