Compared with the conventional contact ultrasonic motor, the non-contact type one resolves the problems caused by friction, such as shorter life expectancy and continuous running time. So it is a new research direction in the field of the ultrasonic motor. This paper introduced a new non-contact ultrasonic motor with fluid medium. The structure, the operating principle and running characteristics of the motor are proposed. In the theoretical analysis and experiments, the saturated flow velocity of the motor is studied. This paper analyses the cause of the saturation, determines that the saturated flow velocity has relations with the depth of the fluid, the concentration of the solution, the nonlinear parameter of the fluid, and applies some methods to increase the saturated velocity. The relationship between the rotor structure and the motor's rotating speed has also been researched. The experiments show how the diameter, the height, the blade number and the material of the rotor influence the motor's rotating speed, and give guides to select the appropriate rotor structure that is advantageous to increase the motor's rotating speed.