An　experimental　investigation　was　performed　on　the　effects　of　the　temperature,　pressure,　equivalence　ratio,　and　fuel　concentration　on　ignition　delay　times　of　dimethyl　ether　(DME)/O-2/Ar　mixtures　behind　the　reflected　shock　wave.　Experimental　conditions　used　temperatures　over　1000-1600　K,　pressures　of　1.2-20　atm,　and　equivalence　ratios　of　0.5-2.0,　with　fuel　concentrations　of　0.5-2.457%.　The　measurements　showed　that　the　DME　mixtures　have　different　global　activation　energies　under　different　equivalence　ratios.　Thus,　correlations　were　derived　under　different　equivalence　ratios　based　on　all　experimental　data,　which　fits　fairly　well　with　the　experimental　data.　Four　recently　developed　models　were　compared　to　the　measurements,　and　their　predictabilities　were　thoroughly　discussed.　Finally,　a　systematic　kinetic　chemical　analysis　was　performed　to　chemically　interpret　the　observed　equivalence　ratio　dependence　and　to　ascertain　the　key　reactions　that　control　ignition　of　DME,　which　are　the　potential　candidates　for　improvement　of　LLNL　DME　Mech.