The　digital　image　holograph　interferometry　technique　was　used　to　measure　the　mass　diffusion　coefficient　of　liquid-liquid　and　gas-liquid　fluids　with　self-built　experimental　set-up.　The　mass　diffusion　coefficients　of　diethyl　carbonate　were　separately　measured　in　heptane　and　in　air　at　21　different　temperatures　from　278.15　to　338.15　K　under　atmospheric　pressure.　The　mass　diffusion　coefficients　of　diethyl　carbonate　in　heptane　were　estimated　by　using　Wilke-chang　equation,　Scheibel　equation　and　Reddy-Doraiswamy　equation,　and　the　experimental　results　were　compared　with　the　values　calculated　by　the　equation.　The　study　provides　the　basic　thermophysical　properties　for　the　development　of　diethyl　carbonate　as　fuel　substitute.