Abstract: The propagation properties of Quasi-longitudinal leaky surface acoustic wave (QLLSAW) on Y-rotated cut quartz substrates are presented . The phase velocity of QLLSAW on the quartz substrate along some orientations can be up from 6,200 m/s to 7,100 m/s, circa 100% superior to that of Rayleigh wave. Both theoretical and experimental results show that QLLSAW propagating along some promising orientations for SAW devices are with small power flow angle and low temperature coefficient, such as along the Euler angle (0°, 155.25°, 42°), the measurements of phase velocity and temperature coefficient of delay of QLLSAW are 6201m/s and 12.9 ppm/ ℃. When liquid was loaded on the face of the substrates, QLLSAW had little absorption by liquid, which depicts that the direction of particle motion is almost parallel to the surface, and demonstrates that the wave is of the properties of longitudinal wave.