Attitude sensing system is indispensable for wireless Micro-Ball endoscopy to capture the full-view images of gastrointestinal (GI) tract. This paper proposes a novel attitude sensing system design with small size and low power for this application, which is based on MEMS 3-axis accelerometer and magnetometer. To reduce the error caused by tilt angles, a compensatory algorithm is introduced in this design. The experimental results show that the attitude sensing system could measure attitude in real time with high enough accuracy meeting the requirement of the wireless Micro-Ball endoscopy application. The power consumption of the attitude sensing system is about 3mW. The error of pitch is less than 3°, roll is less than 3.1°, and yaw is less than 6°.