The transport properties in Hg0.80Mg0.20Te molecular beam epitaxy film has been studied in the temperature range from 15 to 250K by vari able magnetic-field Hall measurement.The experimental data have been analyzed us ing a hybrid approach consisting of the mobility spectrum(MS) technique followed by a multicarrier fitting(MCF) procedure.Both Shubnikov de Hass(SdH) Measuremen ts and the hybrid approach show two- and three-dimensional electronic behaviors. Experimental results indicate that the two-dimensional electrons are due to an a ccumulation layer near the Hg1-xMgxTe-CdTe interface or th e Hg1-xMgxTe-vacuum interface.Ionized impurity scattering of the three-dimension electron mobility dominates at low temperature(considerin g the screening effect) while lattice scattering dominates above 100K.The scatte ring mechanism in Hg1-xMgxTe is very similar to that in Hg 1-xCdxTe.