A new low cost microfluidic device has been designed and fabricated. Three thread microchannels were fabricated using tape and three indicting filter papers were also made by dipping three filter papers into sodium nitrite with different concentration. The side of the thread microchannels was connected to the indicting filter papers and then mounted on a 1280 yx-LiNbO3 piezoelectric substrate, on which an interdigital transducer and reflector were fabricated using microeletric technology. PDMS film was coated to avoid the evaporation of microfluid transporting in the thread based microchannels. When a 25.5MHz RF signal with 25.4dBm power was applied on the IDT, the microfluid on the piezoelectric substrate was actuated by surface acoustic wave and transported along the thread microchannels, and reacted with nitrite ion in the indicting filter paper. Experimental results show that the thread-piezoelectric substrate microfluidic device can be used for biological or chemical analysis.