The DArk Matter Explorer (DAMPE) was launched into a sun-synchronous orbit at the altitude of 500 km on Dec 17, 2015. Its main scientific objective is to detect electrons and photons in the range of 5 GeV$\sim$10 TeV with a high energy resolution. A first investigation to the flight data shows that the trigger system operates quite well. The trigger rate is controlled at a level of 70$\sim$100 Hz except in South Atlantic Anomaly region. This rate is properly high and will not cause much dead time to the detection. The trigger efficiency for high energy electrons is almost 100\%, which makes the detector very suitable for fulfilling its tasks.