Multi-rail lower transom structure for aluminum alloy window

The invention discloses a multi-rail lower transom structure for an aluminum alloy window. The structure comprises a folded plate, a holding plate, a left side body, a first clamping plate, a reinforcing plate, a first screw mounting hole, a support frame, an inclined plate, a second screw mounting hole, a second clamping plate, a right side body, a first support plate, a first slide rail, a second support plate and a second slide rail. According to the invention, a lower transom adopts the form of double rails, and has high hardness; the top of the left side body is bent to form the folded plate, so that a screen window can be installed conveniently, and the function of three rails can be realized even though double rails are arranged, the use range is wide, and the operation and installation are quick and simple; the support frame is additionally arranged at the bottom of the rails to connect and support the two rails, which can not only improve the stability of the connection, but also share the forces on