The high-speed rotation, severe vibration and impact of the drilling tool could cause huge interference to the attitude measurement while drilling in the process of rotary steerable drilling. To address these issues, a drilling tool gravity acceleration extraction algorithm is proposed, which is based on the complementary filtering framework. First, the recursive equation of the gravitational acceleration based on the gyroscope is obtained through the cosine matrix differential equation. Then, the gravitational acceleration of the drilling tool is obtained by fusion under the framework of complementary filtering by using the complementary characteristics of the gyroscope and the accelerometer. Meanwhile, to improve the system′s robustness, the non-gravity acceleration and drilling tool rotation speed are utilized as the input of the fuzzy algorithm. The complementary filter parameters are dynamically adjusted through the fuzzy algorithm. Finally, vibration and rotation experiments are designed to evaluate the effectiveness of the algorithm. Experimental results show that the accuracy of attitude estimation is significantly improved after using the algorithm to extract the gravity acceleration. Compared with the gravity acceleration extraction algorithm based on the Kalman filter framework, the single operation time of the algorithm in the PC test environment is reduced by 31. 9% .