The work aims to test the vacuum packing air tightness with virtual instrument and judge whether food package leaks. Vacuum packing detection system was built. Its signal was measured by pressure sensor and then transmitted to data acquisition card via conditioning circuit. It was ultimately transmitted to the computer. The changed pressure signal was displayed in form of graphics through the virtual instrument that was built by Labview software. Through the experiment, tightness of the vacuum packing was detected with the virtual instrument. Whether the food package leaked was judged. After pressurization, the gradual decrease of pressure inside the vessel with the increase of time indicated that there was leakage while almost unchanged pressure indicated good tightness. In conclusion, it will be an important development direction to test the tightness of vacuum packing with virtual instrument.