A single-axis acoustic levitator driven by a magnetostrictive ultrasonic transducer was developed, which can stably levitate metallic, semiconducting and organic materials as dense as 11.3g/cm3 in ground-based laboratory. Two types of resonant chambers were investigated by using boundary element approachin order to well understand the effect of chamber geometry on the sound field and, more importantly, on the capability and stability of acoustic levitation. The calculated results and experimental research indicate that the chamber possessing both a planar and a conical reflecting surface can produce radial positioning forces at the lowest mode. This makes its positioning capability larger than that of the chamber with only a planar reflecting surface.