Pressure change characteristics of a field emission display (FED) panel in operation was studied with Various operating conditions. For this study, low anode voltage FED samples with a vacuum gap of 0.2 mm were fabricated using unique process technologies of cathode, anode, spacers, and packages. With the FED samples, real-time pressure measurements were carried out during operation of the FED panel with a forced increase of an anode current and/or an anode voltage. Results from the experiment suggest that the pressure buildup of the panel in operation is mainly affected by an electron flux density rather than an electron energy in the low anode voltage FED.