Is there a requirement for hair color when applying for a passport?

The National Immigration Bureau doesn't require hair color. As long as you enter another country, local immigration officials don't mind. However, we all know that China people should have black hair, except ethnic minorities. If the hair color affects the trip, it will not be worth the loss. After all, it takes ten years to issue a passport at a time, so when you apply for a passport, you dye your hair back to black. Don't be individualistic in this respect.