When the price limit is entrusted to bid, the computer automatic matching system sorts the trading declarations according to the principle of "price first, time first". When the buying price is greater than or equal to the selling price, the matching transaction price is equal to the middle value of the buying price (bp), the selling price (sp) and the previous transaction price (cp). That is, when bp≥sp≥cp, the latest transaction price =sp When bp≥cp≥sp, the latest transaction price =cp When cp≥bp≥sp, the latest transaction price =bp.