  Galactic diffuse TeV gamma-ray emission is produced by the interaction of
high-energy cosmic-ray particles with matter and radiation in our Galaxy. The
measurement of Galactic diffuse TeV gamma-ray emission would provide strong
constraints on the acceleration and propagation of Galactic cosmic rays. The
High Altitude Water Cherenkov (HAWC) Observatory, located in central Mexico at
4100 m above sea level, is sensitive to gamma rays between a few hundreds GeV
and about 100 TeV. Thanks to its large field of view of 2 steradians and
excellent background estimation, HAWC has a unique capability to observe large
extended sources such as Galactic diffuse emission. We present the analysis
strategy to detect the Galactic diffuse emission with HAWC, including
techniques to remove contaminations from localized sources.
