This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) based on micro electromechanical system( MEMS) inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs. This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles (UAVs), which uses strapdown inertial navigation system (SINS) based on micro electromechanical system (MEMS) inertial sensors, commercial GPS receiver , and 3-axis magnetometer. MEMS-SINS initial attitude determination can not be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability, therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration. Still more, the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situations. Additionally, the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies th e requirement of attitude measurement for small UAVs during GPS signal outage and availability. Finally, the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous, reliable and effective attitude information for small UAVs.