The core system of the bank is an IT system mainly dealing with the most basic deposit and loan business of the bank, and the trading platform therein reflects the core of the bank and even the overall IT service capabilities. In order to improve the service capability based on the centralized architecture core system during peak trading hours, this study designs a core platform with transaction grouping service. The core platform covers a three-tier architecture of a trading server, a trading distributor, and a trading processor. The transaction grouping service algorithm is used to implement processing tasks grouped by transactions and dynamically allocate system resources. The experimental results show that compared with the traditional two-tier structure core trading platform of monitoring and distribution, the core platform with a three-tier structure with grouping services designed in this study has higher concurrent processing capabilities, and more stable system resource usage.