The invention discloses an auxiliary welding tool fixture of a T-shaped connector laser welding robot for aluminum alloy sheets. The fixture includes a framework, one end of the framework is providedwith an end plate, the other end of the framework is provided with an idler wheel type clamp, the end plate includes a switching mechanism of a first connector and a second connector, and the first connector is provided with a base, a shaft shoulder in which two grooves are distributed radially and evenly, and a connection shaft of a clamping groove; the second connector is provided with a connection plate and a connection sleeve in which two convex blocks and top screw holes are radially and evenly distributed, the connection sleeve cooperates with the connection shaft, the convex blocks cooperate with the grooves, and the top screw holes cooperate with the clamping groove; the idler wheel type clamp includes a clockwise rolling device and two wing-shaped brackets at the two sides, the clockwise rolling device includes a standard unidirectional air cylinder with double guiding rails, a wedge-shaped support with an opening facing downwards and rolling wheels, each wing-shaped support is provided with a bidirectional tightening air cylinder with a standard opening and lateral rolling clamps of two supporting plates, and the bottom of each supporting plate is provided with a pair ofrolling wheels. By adopting the auxiliary welding tool fixture of the T-shaped connector laser welding robot for the aluminum alloy sheets, the accurate control over the size and position of T-shapedconnectors and the rigid fixation of the T-shaped connectors can be achieved, and it is ensured that stringers are prevented from getting misaligned and limiting the welding deformation amount.