This paper presents a simple process technique for the fabrication of valveless micro-pumps. The process design utilizes standard MEMS process using double-sided anisotropic silicon wet etching process with an additional adhesive bonding technique. The diffuser and nozzle element of the pump with depth of 50 µm, as well as a 150 µm thick silicon membrane are designed and fabricated using only 3 patterning process steps. A piezoelectric plate working at the frequency range from 0.1 kHz to 2 kHz is bonded on to the back side of the silicon membrane to create the membrane actuation. The patterning process of thick photoresist used as the adhesive layer for the substrate bonding is also discussed in detail. The fluid flow is observed and the process reproducibility is proven which show a good prospect for the future development of miniaturized valveless pump for biomedical application.