The trend of further research of the micro flow sensor is higher quality factor and sensitivity in the field of velocity measurement. In this letter, a new type of double-ended enhanced film resonance structure was proposed to obtain high quality factor of the Lamb wave sensor. The vector measurements of the liquid flow velocity can be achieved by using the evanescent wave, which exists around the membrane-liquid interface of one antisymmetric mode(A01) of this Lamb wave sensor. The quality factor for the prominent peak of the A01 mode reaches 703. There is a linear relationship between the phase frequency shifts of A01 mode and the value of fluid velocity, while the direction of flow velocity can be judged by the phase frequency shifts direction. Correspondingly, the sensitivity of flow velocity measurement is about 270 Hz/mm/s. As the maximum noises of A01 mode is less than 02 Hz, the limit of detection of the flow velocity(LOD) is 2.2 μm/s and the flow rate(LOD) is 18.3 nL/min. The results demonstrate that the vector measurements of the liquid flow velocity can be actualized with high sensitivity by the double-ended enhanced Lamb wave sensor.