The invention discloses an aerodynamic racing car unit with a high lift-drag ratio variable tail wing. The aerodynamic racing car unit comprises a front wing, a tail wing and a variable tail wing system, wherein the front wing comprises a front wing main wing, two symmetrical external flaps and two sets of internal flap units; the internal flap units are symmetrically positioned on the inner sides of the two external flaps; the tail wing comprises two large end plates, a tail wing main wing, a first reducing wing, a second reducing wing, a first flap and a second flap; the tail wing main wing is fixedly arranged between the two large end plates; the first flap and the second flap are movably arranged between the two large end plates; the tail wing main wing is positioned at the foremost end; the first flap is positioned at the tail end of the wingtip of the tail wing main wing; the second flap and the first flap are arranged at the tail end of the wingtip of the first flap and have a small part of overlap and clearance; the variable tail wing system is in drive connection with the first flap and the second flap. The lift force, drag force and airflow are fully and comprehensively considered, and the aerodynamic racing car unit is an aerodynamic racing car unit for undergraduate formula cars with high negative lift and low drag variable tail wings.