A fabrication method about single-walled carbon nanotube (SWCNT) network and polydimethylsiloxane (PDMS) based composite thin film is reported, which can be used as flow sensor cell. This composite thin film is immersed in deionized water and salt solution with different flow rate tests. The morphology of SWCNTs on the surface of the composite thin film is characterized by scanning electron microscopy, revealing the SWCNTs are coated by PDMS chains. The induced voltage generates along the direction of the flowing liquid and depends significantly on the ionic concentration and flow velocity. Since the SWCNTs are fixed into PDMS matrix, the I-V curves of the composite thin film before and after several flow velocity measurements are exactly coincident, and the repeating flow-induced voltage experiment shows the composite thin film has a reliable electric characteristic and wide potential of device application.