During phase 1（2001—2008） of Japan Methane Hydrate R&D program（MH21）and later, Japan participated in NGH production tests in permafrost zone in Canada Mallik and US Alaska; In 2000 and 2004, a exploration well and a multiplewell coring project were respectively executed. Since the beginning of phase 2（2009—2015） of the MH21, Japan had strenthened the drilling and coring studies for methane hydrate reservoir in Eastern Nankai Trough with CDEX hybrid PCS, as well as comducted fine analysis and characterization for coring samples of hydratebearing sediments under pressure with Pressure Core Characterization Tools（PCCT）, etc.; The strategy of Environmental Impact Assessment（EIA）study was put forwaded, and EIA methodology seriously was applied, as well as monitoring systems for offshore production tests, including Methane Leakage Monitoring System (MLMS), Seafloor Deformation Monitoring System (SDMS) etc., were deploied. Japan completed offshore methane hydrate production testmethane producrd from deepwater hydrate layers in the Eastern Nankai Trough in 12—18 of March, 2013. Cumulative volume of gas production was 120000m3 in 6 day, average volume of gas production——20000m3/day. This is the first offshore methane hydrate successful production test in the world, and a milestone in NGH development history in the world. At the same time, the NGH commercial production will be internationally a very difficut and long period.