Abstract: Rotary steering drilling is a new drilling technique developed in 1990s. It takes rotary steering drilling system as the core. The rotary steering drilling system is mainly composed of three parts, i.e., the downhole rotary steering drilling tool system, the bi-directional communication system, and the surface monitoring system. After briefly introducing the development conditions of the system both at home and abroad, this paper lays emphasis on analyzing the main factors influencing the controlling accuracy of the rotary steering drilling motor, i.e., the selection of sensors, various calculating methods, and the features of tool system. Discussion is mainly made on the selection of attitude control sensors, how to eliminate the errors caused by system inertia, and the relationship between the sampling rate and the tools resolution. What’s more, experiments are conducted to illustrate the subject. Some understandings of how to improve the controlling accuracy of the rotary steering tools are developed, laying theoretical basis for the accuracy control of steering tools.