The following are some cases of bank cards being frozen when withdrawing Bitcoin in mainland China:

- Case of Mr. Peng: After graduating from university, Mr. Peng worked in internet operations and started trading virtual currency through a friend's introduction. In December 2019, his bank card was suddenly frozen by the Guizhou Provincial Public Security Bureau, on the grounds of suspected virtual currency trading. After the assistance of a lawyer team, Mr. Peng's bank card was successfully unfrozen.

- Case of Ms. Wang: Ms. Wang is a university graduate with a major in computer science, frequently trading Bitcoin for cash on digital currency trading platforms. Because her trading platform only provided support for digital currency transactions and did not offer support for fund payment settlements, the fund exchange was conducted offline, resulting in her account being linked to criminal accounts. As a result, over 500,000 yuan in her account was frozen by a public security bureau in Henan. After representation by a lawyer team, her account was successfully unfrozen.

- Case of OTC merchants and players: In 2020, a wave of frozen cards occurred in the cryptocurrency space, and some merchants and players participating in OTC trading had their bank cards frozen. For example, a Weibo user sold coins for 50,000 yuan through the Huobi OTC trading area on March 9, 2020, and subsequently, their bank card was frozen.

These cases indicate that withdrawing Bitcoin and other digital currencies in mainland China carries the risk of bank cards being frozen. The main reason is that the anonymity and convenience of digital currency trading can be exploited by criminals for money laundering and other illegal activities, leading to related accounts being investigated and frozen by public security agencies.