This paper concerns attitude control of a moving mass-actuated fixed-wing unmanned aerial vehicle (MFUAV). Unlike conventional roll motion of UAV, which is controlled by ailerons, this MFUAV uses the movement of mass block inside the wing to generate roll moment. It is difficult to design a suitable attitude controller for it due to the strong non-linearity and coupling of the MFUAV dynamics. Linear active disturbance rejection control (LADRC) proved to be a simple and effective alternative to conventional PID control. LADRC is able to eliminate disturbances with the help of extended state observer (ESO) and does not depend on the accurate mathematical models of particular systems. Finally, simulation results show that the attitude tracking control of MFUAV is well achieved with robustness. This shows that the designed method is easy to adapt and implement during the actual flight of the MFUAV.