Abstract: The corporate defects mean that there has been some disqualifications of both conditions and procedures in the process of incorporation. When the incorporation has some defectives, the "de facto corporations" and "corporations by estoppel" in common law is conditional ratification of a legal entity, while the invalid incorporation system in Roman law is to deny the status of a corporation by suit. We should set up the invalid incorporation system in our company law, and at the same time conditionally ratify the legal status of a company under special circumstances.