To obtain real-time water contents and temperatures of vacuum freezing drying process, and to facilitate monitoring of drying process, a novel online measuring system (OMS) for vacuum freezing dryer was proposed and experimental tests were carried out. The system was composed of a microcontroller, a strain pressure sensor, a thermal resistance, modulus conversion modules, an OLED screen and other components. Wireless data transmission was used, and temperature correction and vibration reduction were carried out in the design. Experimental tests showed that the system could be used to measure the weight, moisture content and temperature in real time during the vacuum freezing drying process, and the relative deviation between the weight measurement value and the actual value was 1.6%~2.7% in the range of 5~50 g. For the temperature, the deviation was within ±3% in the range of 40~40 ℃, indicating a good accuracy.