In order to obtain a high sensitive Love wave mass sensor, the Love wave propagation characteristics in a layered structure consisting of a ST-quartz and a silica were investigated theoretically and experimentally on the basis of acoustic dynamics,the wave equation for the layered structure was analyzed and its displacement and the dispersion curves were obtained by calculation. According to the computing results, a Love wave sensor with a SiO2 waveguide layer was designed and fabricated on a ST-quartz substrate by MEMS processes and its sensitivity was tested by electro-deposition experiment. The results indicate that the mass sensitivity of the device is 100 cm2/g and the detection limit is 3.65 ng,which meets the demand of biochemical detection for higher sensitivity basically.