A　visual　observation　of　liquid-gas　two-phase　flow　in　anode　channels　of　a　direct　methanol　proton　exchange　membrane　fuel　cells　in　microgravity　has　been　carried　out　in　a　drop　tower.　The　anode　flow　bed　consisted　of　2　manifolds　and　11　parallel　straight　channels.　The　length,　width　and　depth　of　single　channel　with　rectangular　cross　section　was　48.0　mm,　2.5　mm　and　2.0　mm,　respectively.　The　experimental　results　indicated　that　the　size　of　bubbles　in　microgravity　condition　is　bigger　than　that　in　normal　gravity.　The　longer　the　time,　the　bigger　the　bubbles.　The　velocity　of　bubbles　rising　is　slower　than　that　in　normal　gravity　because　buoyancy　lift　is　very　weak　in　microgravity.　The　flow　pattern　in　anode　channels　could　change　from　bubbly　flow　in　normal　gravity　to　slug　flow　in　microgravity.　The　gas　slugs　blocked　supply　of　reactants　from　channels　to　anode　catalyst　layer　through　gas　diffusion　layer.　When　the　weakened　mass　transfer　causes　concentration　polarization,　the　output　performance　of　fuel　cells　declines.