The invention relates to a measuring and controlling device used for a rotary steering drilling system and a measuring and controlling method utilizing the same. The device comprises a microprocessor module, a data acquisition module, a driver module, a data communication module, a data storage module and a power management module. The method comprises the following steps: 1) carrying out pressure pulse coding on the control instruction on the ground and transmitting the code to the microprocessor module under the shaft; 2) carrying out system initialization and self check and checking whether a main CPU (central processing unit) works normally, if no, switching to a redundant CPU; 3) using the microprocessor module to decode the pressure pulse to obtain the instruction transmitted by the pressure pulse; 4) using a system to acquire data and calculating the deviation angle and high-side tool face angle of the position of a current rotary steering drilling tool, the eccentric displacement of the current rotary steering drilling tool and the displacement extension of an actuating mechanism; and 5) decoding the pulse instruction, carrying out PID (proportion integration differentiation) control on the calculated displacement extension of the actuating mechanism and adjusting the displacement extension of the actuating mechanism. The device is used for the static biased directional rotary steering drilling tool, and can be used for accurately measuring the eccentric displacement of the tool and simultaneously controlling the expansion amount of wing ribs more accurately.