Micro-electric discharge milling (μED milling) has the potential to create micro-channels in metals. Since μED milling is a slow machining process, the requirement of strategies that can enhance the material removal rate (MRR) is always crucial in the field of micro-machining. Nano-powder-mixed micro-electric discharge milling (NPMμED milling) is least explored by researchers. Also, the behaviour of μED milling at various discharge energy regime (D.E.R) was not analysed extensively. The present study investigates the combined effects of nano-powder-mixed dielectric at three different regimes of discharge energies with respect to MRR and tool wear rate (TWR) while micro-machining of Ti-6Al-4V using cryogenically treated electrodes. There is significant difference in the machining behaviour at low, medium and high D.E.Rs. Also, the effects of transformation in cathodic streamers due to addition of nano-graphene powders in the dielectric fluid were extensively analysed. Cryogenic treatment of the tool electrodes gave better MRR. The addition of nano-powders in the dielectric has reduced the crater diameter significantly however increased the overall 3D roughness of the machined surface. © 2019, Springer-Verlag London Ltd., part of Springer Nature.