Abstract: The influence of control surfaces deflection on lateral-directional characteristics of a tailless aircraft with multiple control surfaces was investigated in a wind tunnel using force measurement. Both single deflection and simultaneous deflection of elevons and flaperons have a good effect of lift increment, while all-moving tips (AMTs) deflection leads to a reduction in lift before stall. The influence law of control surfaces deflection on the yawing moment control is not significant. However, single deflection of the AMT has a better effect on the yawing moment control than elevons and flaperons. Both single positive deflection and simultaneous positive deflection of elevons and flaperons result in a negative rolling moment, and the increment is much more significant with a larger deflection angle. Elevons have a better effect on the rolling moment control than flaperons, while AMTs have little influence on the rolling moment control. Besides, the control efficiency can be improved obviously adopting simultaneous deflection compared with single deflection.