According to the regulations of China's public security department, the household registration book is an important document to record personal basic information, including parents' ID numbers. By looking at the relevant information in the household registration book, you can get the ID number of your parents. Household registration books are generally managed and issued by local police stations or neighborhood committees. If you need to check your parents' ID numbers, you can go to the local police station or neighborhood committee to provide relevant personal information and application materials, such as ID cards and household registration books.