A novel micropump actuated by NiTi/Si composite diaphragm was described in this paper. The driving principle, microfabrication processes and characteristics of the pump were reported. The pump is composed of a deformable chamber and two silicon flap check valves. The outer dimension of the pump is 6mmx6mmx1.5mm, with the diaphragm size of 3mmx3mmx20μm. The fabrication processes include silicon micromachining and Au Si eutectic bonding. By using the recoverable force of NiTi thin-film and biasing force of silicon membrane, the actuation diaphragm realized reciprocating motion effectively. Experimental results show that the pump has superior performance, such as high pumping yield (up to 340μl/min), high working frequency (up to 100Hz), and long fatigue life time (more than 4x10 7 working cycles).