If you convert Hong Kong dollars into RMB, the price of cash is higher than that of cash. Just take my ID card and a copy (left by the bank) and exchange it at the counter of your branch or office in China Bank on normal working days.
If cash is converted into RMB, it must be converted into RMB first. More than 500 thousand yuan (inclusive), but also to provide the corresponding legal income certificate. If it's below, you can change it directly with the original ID card, and you don't have to fill in anything.