Abstract: Virtual Instrument(VI) is becoming a popular tool in measurement, test and automation owing to fast development of computer platform. In this paper, according to the process demand of thin layer drying, a unique thin layer drying experimental system based on the incremental PID control algorithm and pulse width modulation(PWM) is developed using virtual instrument software—LabVIEW. The precision of controlling temperature is ±0.5℃; sample moisture and moisture removal rate are auto supervised through acquiring the sample mass intermittently; drying air temperature and humidity, exhaust air temperature and humidity, sample mass, and moisture removal rate etc. are shown as chart in time and stored in Microsoft Excel spreadsheet file for processing. Practical application of this system shows that its automaticity is high, the experimental operation is agile, the user interface is friendly, the data processing and analyzing functions are powerful and the measurement results are precise.