The current A-share trading system is a T+1 trading system, and there is a limit on the rise and fall; while the current Hong Kong stock market can be freely bought and sold during the trading session of the day, with no restrictions on the number of transactions and the rise or fall. T+0 trading system. During the stock trading process, each lot of A-shares is uniformly divided into 100 shares as one trading unit, while the trading unit of each lot of Hong Kong stocks is mainly determined based on the price of the stock, and there is no unified regulation. Generally speaking, there are 400 shares, 500 shares, etc. Shares, 1,000 shares, 2,000 shares, 10,000 shares/lot. This is also the main reason why some investors often fail to buy the entire position or the number of shares purchased is inaccurate and the transaction is canceled. In addition, it is worth noting that when A-share investors buy and sell stocks, securities companies can provide free market software; in the Hong Kong market, market software requires separate fees from investors. The settlement system and the difference between deposits and withdrawals of funds. Currently, A-shares implement a T+1 settlement system. In terms of fund management, banks carry out third-party custody; the Hong Kong stock market currently adopts a T+2 settlement system. When stocks are sold, After submitting the withdrawal application to the bank where the account is opened, it will take the second working day to transfer the funds. The fund custody is implemented by a third party, such as HSBC, Hang Seng Bank, Bank of China (Hong Kong), Standard Chartered and Liu Chong Hing Bank. , customers need to fill in a special form for securities companies to withdraw funds or transfer stocks to custody, and sign and be verified by the Legal Department before they can transfer. Therefore, the investor's account opening signature style is very important, as it is the legal basis for fund deposits and withdrawals. Differences in trading varieties: The existing trading varieties in the A-share market are mainly stocks and funds, and there are also some warrants, convertible bonds and other varieties; while there are many trading varieties in the Hong Kong stock market, in addition to stocks, stock index futures, funds, In addition to warrants, it also has various derivatives such as high-interest bills, stock short selling, options, stock-linked bills, etc., and can implement margin account (overdraft) trading.