An online transaction system was developed to meet needs of online exhibition and electronic trading platform construction for rural farm produce markets through applying the software tools Studio.NET 2005 and Microsoft SQL Server 2005. Function module structure of farm produce online transaction system was designed, system data flow chart and data entity attributes were described, typical system interfaces were given, and corresponding business process was summarized, based on the current state analysis of rural farm produce markets. Practices showed that this platform system with functions such as information release and online transactions, had improved the business efficiency and informatization construction level of farm produce trading. Designment and realization of online transaction system provided a solution for informatization construction of rural farm produce markets, and this system makes characteristic agriculture products more convenient and efficient to be exchanged.