1997 is the year that H.K. returned to China. Many institutes in H.K., including Bank produced medals as gift to their customers in commemorating the event. Most medals were made with copper or silver by local private mints. Please note that Bank of China (commercial bank) and People’s Bank of China (central bank of China) are not the same.
This medal appears to be special, expensive, and nicely made. Bank of China (Hong Kong branch) is one of the three official banks in H.K. can issue H.K. banknote. Therefore, IMO, this medal may be minted by H.K. Mint or a private mint in H.K. and it has nothing to do with China Mint.