High bonding strength, low deformation and convenient procedure are all very important aspects in the microfluidic device fabrication process. In this paper, an improved microwave induced bonding technology is proposed to fabricate microfluidic device based on methyl methacrylate (PMMA). This method employs pure ethanol as the bonding assisted solvent. The ethanol not only acts as the microwave absorbing material, but also works as the organic solvent in bath. The presented research work has shown that the bonding process can be completed in less than 45 s. Furthermore, the convenient bonding only applies microwave oven, beakers and binder clips. Then, we discuss effects of microwave power, bonding time on bonding strength and deformation of microstructures on PMMA microfluidic device. Finally, a 4 layers micro?mixer has been fabricated using the proposed bonding technique which includes 15 trapezoid micro?channels, 9 T?type mix units and an X?type mix unit. Experimental results show that the proposed bonding method have some advantages compared with several traditional bonding technologies, such as hot pressing bonding, ultrasonic bonding and solvent assisted bonding methods in respect of bonding strength, deformation and bonding process. The presented work would be helpful for low coat mass production of multilayer polymer microfluidic devices in lab.