Airfoil slotted is a passive flow control technology to improve the stall characteristics of airfoil by using slot jet. In order to explore the influence of the slot parameters change on the aerodynamic characteristics of multi-element airfoil, the CFD method is used to study the slotting of GAW-1 two-element airfoil in the paper. Nine kinds of slot configurations are designed, and the geometric relations among three types of slot configurations, namely straight line, curve and deflector, are given, and a curved trapezoidal slot configuration is proposed. It is found that the slot position is the key factor to restrain the stall development of airfoil, and the optimal slot position of curved trapezoidal slot configuration is 13.5% c; the slot has the strongest ability to restrain stall, the stall angle of attack of airfoil is delayed by 7°, and the maximum lift coefficient is increased by 19.5%, reaching 3.89. Finally, the influence of the deflector slot configuration on the aerodynamic characteristics of the airfoil is studied. The deflector slot configuration can not only weaken the damage of the slot to the aerodynamic characteristics at a small angle of attack, but also slow down the stall development and improve the stall characteristics of the airfoil. In this paper, the research ideas and results of slotted multi-element airfoil can provide a reference for the subsequent research of other slotted multi-element airfoil.