An　in-situ　visualization　of　two-phase　flow　inside　anode　flow　bed　of　a　small　liquid　fed　direct　methanol　fuel　cells　in　normal　and　reduced　gravity　has　been　conducted　in　a　drop　tower.　The　anode　flow　bed　consists　of　11　parallel　straight　channels.　The　length,　width　and　depth　of　single　channel,　which　had　rectangular　cross　section,　are　48.0,　2.5　and　2.0　mm,　respectively.　The　rib　width　was　2.0　mm.　The　experimental　results　indicated　that　when　the　fuel　cell　orientation　is　vertical,　two-phase　flow　pattern　in　anode　channels　can　evolve　from　bubbly　flow　in　normal　gravity　into　slug　flow　in　microgravity.　The　size　of　bubbles　in　the　reduced　gravity　is　also　bigger.　In　microgravity,　the　bubbles　rising　speed　in　vertical　channels　is　obviously　slower　than　that　in　normal　gravity.　When　the　fuel　cell　orientation　is　horizontal,　the　slug　flow　in　the　reduced　gravity　has　almost　the　same　characteristic　with　that　in　normal　gravity.　It　implies　that　the　effect　of　gravity　on　two-phase　flow　is　small　and　the　bubbles　removal　is　governed　by　viscous　drag.　When　the　gas　slugs　or　gas　columns　occupy　channels,　the　performance　of　liquid　fed　direct　methanol　fuel　cells　is　failing　rapidly.　It　infers　that　in　long-term　microgravity,　flow　bed　and　operating　condition　should　be　optimized　to　avoid　concentration　polarization　of　fuel　cells.