In order to optimize the drying technique and provide the quality-control system with theoretical data, based on hot air cross-flow drying principle, the auto-control system for cross-flow drying test equipment was manufactured, using modularized designing, and intelligent instruments such as programmable controller and computer as main controller. The system can be used to control airflow rate, temperature and time. It can be used to optimize the technical parameters of the drying technology with various materials in the test equipment. It was proved that the auto-control system is good at high level of precision, automatization, adaptability, simulation, credibility, and it is suitable for drying experimental research for agricultural byproducts.