The microstructure and field emission properties of multi walled carbon nanotubes (MWNTs) were investigated. The comparisons are made between MWNTs synthesized by high temperature arc methods and low temperature CVD methods. The results of the HRTEM image clearly exhibit characteristic features of a multi walled carbon nanotube. Raman spectrum shows a stronger peak at about 1580 cm-1 indicating the formation of a well-graphitized carbon nanotube. It also shows the high temperature arc process can produce MWNT that has perfect graphitic layer structure and high I(G)/I(D) ratio. The Ratio of G-line (sp2 bond) and D-line(sp3 bond) of these MWNTs are about 2.8 to 5.2. From the field emission measurement, the low onset field is about 1.4 to 2.4 V/ m, and can be attributed to highly sharp tips and high electric conductivity of MWNTs.