8%。 The temperature and humidity monitoring and controlling system in a tunnel-type dryer was developed, based on supervisory control and data acquisition (SCADA) systems, industrial personal computer (IPC) and programmable logic controller (PLC). The customized IPC software of monitoring and controlling system monitors real-time temperature and humidity through the communication between IPC and PLC. The software functions realized drying processing parameters inputting, real-time data acquisition and displaying, dynamic and historical data curves, database inquiry and report forms printout. The accuracy of temperature and humidity controlling meets with the requirement of the drying room, with the maximum track error as 2℃ for temperature and 8% for relative humidity.